Visibility and position of the planets in the sky during the month.

June, the "brightest" month, does not really favor astronomical observations. If in the south the nights are simply short, then in temperate latitudes the period of white nights begins at all. The bright planets, the Sun and the Moon remain almost the only available objects for observation.

All four bright planets can be seen in the June sky this year. Jupiter is visible in the first half of the month in the evenings in the west, beautiful Venus throughout June - in the mornings in the east. In the evenings, Mars and Saturn can be observed in the south and southwest. These two planets are the most convenient for observations in June.

But we will begin our review with Mercury, the planet closest to the Sun.

Mercury

Mercury minutes before its occultation by the Moon in the daytime sky of Sochi on June 26, 2014.

At the beginning of June, the period of evening visibility of Mercury ends. The planet closest to the Sun could be observed in the first days of the month low in the northwest for about half an hour after sunset, and only in the south, outside the zone of white nights. Almost all of June, Mercury is in the sky near our day star and therefore is not available for observation. On June 19, the planet enters into inferior conjunction with the Sun, that is, it will pass between the Earth and the Sun, after which it passes into the morning sky.

On June 26, Mercury, being in the sky only 10 ° from the Sun, will be covered by the Moon. This interesting phenomenon will be observed in the Atlantic, America and Europe, in particular, in the Crimea and on the Black Sea coast of the Caucasus. The occultation will begin around 5 pm when the Moon and Sun are in the western sky.

The brightness of Mercury will be about 2.5m, which, in principle, allows you to see the planet against a blue sky background in a good amateur telescope. However, be extremely careful! Don't forget that plating will occur near the Sun and the star's rays can accidentally hit the eyepiece and damage your eyesight! We would recommend observing this phenomenon only to experienced amateurs. For our part, we will try to publish interesting photos of the coverage, if any appear on the Internet.

Venus

Have you seen Venus yet this summer? In early June, the Morning Star rises about an hour before sunrise over the eastern (more precisely, over the northeast-east) part of the horizon.

However, the period of visibility of Venus is rather arbitrary: in Ukraine, in the Crimea and the Caucasus, the planet is currently visible for almost 1.5 hours, appearing in a dark sky. At the latitude of Moscow, the period of visibility of Venus does not reach even up to an hour. Even further north, in view of the white nights, even less. At the same time, the planet rises against the background of the dawn. But you can still find it in St. Petersburg because of the great brightness of the planet (during June it stays around -4m). Note that at the time of rising, Venus, which is actually white, can be red, orange and deep yellow, confusing the beginner. In this case, we are faced with the typical reddening of space objects near the horizon due to dust floating in the Earth's atmosphere.

What will happen in the sky with Venus during the month? I must say that throughout June the planet has a direct movement (that is, it moves against the background of stars in the same direction as the Sun, from west to east), moving along the constellation Aries. Venus is gradually catching up with the star in the sky, but in June the distance is reduced slightly - from 37 to 30 degrees. The position of the planet's rising point is slightly shifted to the north.

30 degrees from the Sun is a very comfortable distance to observe such a bright planet in the predawn sky. However, in temperate latitudes and in the north, white nights intervene, which somewhat complicates its observation. But in this case, as we said above, Venus can be seen quite easily with the naked eye, not to mention observations through a telescope or binoculars. Before sunrise, the planet has time to rise into the sky at the latitude of Moscow by about 10 °, at the latitude of Sochi - by 15 ° above the horizon.

Perhaps it is after sunrise that the June observations of Venus through a telescope will be most interesting and productive. Already in the morning, the planet rises high enough above the horizon that atmospheric turbulence does not greatly distort the picture in the eyepiece, and the low contrast between the dazzling white Venus and the blue background of the sky often allows you to notice much more detail in the planet's cloud cover than usual.

During June, the apparent dimensions decrease from 14 to 12 arc seconds, and the phase increases from 0.77 to 0.86. (The planet, following a smaller orbit, overtook the Earth and is now moving away from it, and in a few months will hide behind the Sun.)

Venus and the Moon in the morning sky on June 24th. The dimensions of the moon are increased by 4 times for clarity.

I must say that during the day it is quite possible to see Venus with the naked eye. To do this, it is enough to isolate oneself from the bright Sun and consider a section of the sky 30 ° to the right of the star. In the first half of the day, Venus will be slightly above the Sun, in the second, respectively, below. Finally, on June 24, an excellent reference point for finding Venus, both before sunrise and in the daytime sky, will be the “aging” Moon, the narrow crescent of which will approach the planet up to 3.5 °.

Mars

It's been 2 months since Mars' opposition in April. The brilliance and apparent size of the Red Planet have decreased significantly and continue to decrease rapidly. However, in June, Mars remains one of the most visible celestial bodies during the evening and night hours.

The entire month the planet is in the constellation Virgo, moving against the background of the stars in the same direction as the Sun and gradually approaching Spica, the main star of the constellation Virgo. Mars appears in the evening twilight in the southwest at 25 ° above the horizon (at the latitude of Moscow). The planet can be distinguished from stars by its characteristic pinkish color and even radiance (stars tend to twinkle noticeably).

At the beginning of June, the visibility of Mars is about 4 hours, at the end - only 2 hours. The brightness of the planet decreases from -0.5m to 0.0m, the diameter of the visible disk is from 11.9″ to 9.5″. In a good amateur telescope with a lens of 120 mm or higher, a lot of interesting details can be found on the planet's disk - polar caps, dark and light areas, areas with various shades of yellow, red and even blue. And in modern digital images, the Mysterious Planet still appears very impressive today.

The planet Mars, photographed on May 7, 2014. The image clearly shows the northern polar cap, dark areas of the Chryse region and bright cirrus clouds.

Jupiter

Saturn, Moon, Mars and Jupiter on the evening of June 8th. Jupiter in the evenings in the first half of June is visible in the rays of the evening dawn low in the northwest.

Shining in our sky for almost a year, Jupiter ends the period of evening visibility in June. The planet moves in the same direction as the Sun, but being farther from us than the daylight, it moves against the background of stars slower than the Sun. At the end of July, the Sun will catch up with Jupiter and the planet will again, like last year, move to the evening sky, where on August 18 there will be a remarkable approach to Venus.

In the first half of June, Jupiter can be observed for about 2 hours in the evening twilight in the northwest (90 ° to the right of Mars); at the end of the month, the planet actually hides in the rays of the Sun.

Despite the fact that Jupiter is currently located near the most distant point of its orbit from the Earth, the planet is so large that its brightness and size have not decreased significantly compared to the winter period. In June, Jupiter's brightness is around -1.9m, and the diameter of the visible disk is about 32″. The planet is still perfectly visible even in small telescopes; its observations will be hampered to a much greater extent by the low position above the horizon and the bright background of the sky in temperate latitudes than by the distance from the Earth.

Saturn

The approach of the Moon and Saturn at midnight on June 11, 2014. Please note that Saturn, Mars and the bright star Arcturus form an almost isosceles triangle in the sky in June.

The position of Saturn in the sky makes this planet the most convenient to observe in June 2014. Being in the constellation of Libra all month, the ringed giant appears at dusk in the south at an altitude of 15-20 degrees above the horizon, depending on the latitude of observation. In the south of Russia, Ukraine, Kazakhstan, the visibility of Saturn will be about 6 hours, in temperate latitudes the planet will be visible throughout the short night.

In terms of brightness (0.4m), Saturn is comparable to the brightest stars, but this may not be enough for a beginner to confidently identify the planet in the bright June night sky. Especially for beginner astronomy lovers, we will inform you that in the evening Saturn can be found 30 ° (about 3-4 fists of an outstretched hand) east of the reddish and brighter Mars. When searching, it is important not to confuse Mars with the star Arcturus, which is also reddish and has about the same brilliance as Mars. In general, Mars, Arcturus and Saturn form an isosceles triangle in the June sky, at the base of which are two planets. The easiest way to find the planet will be on the night of June 10-11. At this time, next to Saturn (only 1.5 ° south of the planet), the Moon will be in a phase close to the full moon.

The color of Saturn is yellow. Already in a small telescope one can see the disk of the planet flattened towards the poles and the luxurious rings of the planet opened at 20 °. The visible dimensions of the planet are 18″, and the rings are 40×15″. In a telescope with a lens of 100 mm or more, you can try to see the Cassini Gap in the rings of the planet. Even with smaller instruments, Saturn's largest moon Titan can be seen as an 8.4m star.

Uranus and Neptune

The last planets in our review are Uranus and Neptune. The distant giants are too faint to be observed with the naked eye (only Uranus at opposition can be seen at the limit of visibility on a moonless night). And in most amateur telescopes, they look at best like tiny greenish-blue discs without any details.

Now both Uranus and Neptune are in the morning sky in the constellations of Pisces and Aquarius, respectively. The visibility of Uranus in June is about 1 hour at the beginning of the month and rises to 2 hours at the end. The brightness of the planet is 6.0m, the apparent size of the planet is 3.4″; to see the disk, you will need a telescope with a lens of at least 80 mm and a magnification of 80× or higher. Note that it is almost impossible to observe the planet north of Moscow due to the white nights.

To an even greater extent, the latter also applies to Neptune, which, even if it rises almost an hour earlier than Uranus, has a brightness of only 8m. Like Uranus, Neptune moves across the sky in the same direction as the Sun. It can be found near the star Sigma Aquarii (magnitude 4.8m). To see the disk of the planet, you need a more serious tool: a telescope with a 100-120 mm lens and a magnification of over 100 ×.

We repeat that the search and observation of these planets, due to their remoteness from the Earth, have only cognitive value for amateurs at best.

Let's summarize. In June, all the planets are visible in the sky, except for Mercury, which enters inferior conjunction with the Sun on the 19th. The most favorable conditions will develop for the observation of Saturn and Mars. These two planets appear in the sky at dusk in the south and southwest, respectively. The planets are located at an altitude of about 20 ° above the horizon and are visible for 6 and 4 hours, respectively. In temperate latitudes, Saturn can be observed throughout the short night.

Venus is visible in the east in the morning for about an hour before sunrise. The brilliance of the planet allows you to observe it both during the day, both with a telescope and with the naked eye. Jupiter can still be seen in the evenings in the northwest, in the rays of the evening dawn. Its visibility is rapidly decreasing, and at the end of the month the planet will hide in the rays of the Sun.

Planet Venus

General information about the planet Venus. Sister of the Earth

Fig.1 Venus. A snapshot of the MESSENGER device dated January 14, 2008. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Venus is the second planet from the Sun, very similar in size, gravity and composition to our Earth. At the same time, it is the brightest object in the sky after the Sun and the Moon, reaching a magnitude of -4.4.

The planet Venus has been studied very well, because more than a dozen spacecraft have visited it, but astronomers still have some questions. Here are just a few of them:

The first of the questions concerns the rotation of Venus: its angular velocity is just such that during the inferior conjunction, Venus faces the Earth all the time with the same side. The reasons for this consistency between the rotation of Venus and the orbital motion of the Earth are not yet clear ...

The second question is the source of the movement of the atmosphere of Venus, which is a continuous giant vortex. Moreover, this movement is very powerful and is distinguished by amazing constancy. What kind of forces create an atmospheric vortex of such dimensions - is it unknown?

And the last, third, question - is there life on the planet Venus? The fact is that at an altitude of several tens of kilometers in the cloudy layer of Venus, conditions quite suitable for the life of organisms are observed: not very high temperature, suitable pressure, etc.

It should be noted that there were much more questions related to Venus just half a century ago. Astronomers did not know anything about the surface of the planet, did not know the composition of its amazing atmosphere, did not know the properties of its magnetosphere, and much more. But they were able to find Venus in the night sky, observe its phases associated with the movement of the planet around the Sun, etc. Read about how to make such observations below.

Observation of the planet Venus from Earth

Fig. 2 View of the planet Venus from the Earth. Credit: Carol Lakomiak

Since Venus is closer to the Sun than the Earth, it never seems too far from it: the maximum angle between it and the Sun is 47.8°. Due to such features of the position in the Earth's sky, Venus reaches its maximum brightness shortly before sunrise or some time after sunset. Within 585 days, the periods of its evening and morning visibility alternate: at the beginning of the period, Venus is visible only in the mornings, then - after 263 days, it comes very close to the Sun, and its brightness does not allow seeing the planet for 50 days; then comes the period of evening visibility of Venus, lasting 263 days, until the planet again disappears for 8 days, being between the Earth and the Sun. After that, the alternation of visibility is repeated in the same order.

Recognizing the planet Venus is easy, because in the night sky it is the brightest luminary after the Sun and the Moon, reaching a maximum of -4.4 magnitude. A distinctive feature of the planet is its even white color.

fig.3 Change of phases of Venus. Credit: website

When observing Venus, even with a small telescope, you can see how the illumination of its disk changes over time, i.e. there is a phase change, which was first observed by Galileo Galilei in 1610. At the closest approach to our planet, only a small part of Venus remains consecrated and it takes the form of a thin crescent. The orbit of Venus at this time is at an angle of 3.4° to the orbit of the Earth, so that it usually passes just above or below the Sun at a distance of up to eighteen solar diameters.

But sometimes there is a situation in which the planet Venus is located approximately on the same line between the Sun and the Earth, and then you can see an extremely rare astronomical phenomenon - the passage of Venus across the disk of the Sun, in which the planet takes the form of a small dark “speck” with a diameter of 1/30 solar.

fig.4 Transit of Venus across the disk of the Sun. Image from NASA's TRACE satellite on August 6, 2004. Credit: NASA

This phenomenon occurs about 4 times in 243 years: first, 2 winter passages are observed with a frequency of 8 years, then an interval of 121.5 years lasts, and 2 more, this time summer, passages occur with the same frequency of 8 years. Winter transits of Venus can then be observed only after 105.8 years.

It should be noted that if the duration of the 243-year cycle is a relatively constant value, then the periodicity between winter and summer passages within it changes due to small discrepancies in the periods of return of the planets to the points of connection of their orbits.

So, until 1518, the internal sequence of the passages of Venus looked like “8-113.5-121.5”, and until 546 there were 8 passages, the intervals between which were equal to 121.5 years. The current sequence will continue until 2846, after which it will be replaced by another: "105.5-129.5-8".

The last transit of the planet Venus, lasting 6 hours, was observed on June 8, 2004, the next one will take place on June 6, 2012. Then there will be a break, the end of which will not be until December 2117.

History of exploration of the planet Venus

Fig.5 The ruins of the observatory in the city of Chichen Itza (Mexico). Source: wikipedia.org

The planet Venus, along with Mercury, Mars, Jupiter and Saturn, was known to people of the Neolithic (New Stone Age). The planet was well known to the ancient Greeks, Egyptians, Chinese, inhabitants of Babylon and Central America, the tribes of Northern Australia. But, due to the peculiarities of observing Venus only in the morning or in the evening, ancient astronomers believed that they were seeing completely different celestial objects, which is why they called the morning Venus one name, and the evening one another. So, the Greeks gave the name Vesper to evening Venus, and Phosphorus to morning Venus. The ancient Egyptians also gave two names to the planet: Tayoumutiri - morning Venus and Owaiti - evening. The Maya Indians called Venus Noh Ek - "Great Star" or Ksuks Ek - "Star of the Wasp" and were able to calculate its synodic period.

The first people to understand that Venus morning and evening are the same planet were the Greek Pythagoreans; a little later, another ancient Greek, Heraclid Pontus, suggested that Venus and Mercury revolve around the Sun, not the Earth. Around the same time, the Greeks gave the planet the name of the goddess of love and beauty, Aphrodite.

But the planet got the name "Venus" familiar to modern people from the Romans, who named it in honor of the patron goddess of the entire Roman people, who occupied the same place in Roman mythology as Aphrodite in Greek.

As you can see, the ancient astronomers only observed the planet, simultaneously calculating the synodic periods of rotation and compiling maps of the starry sky. Attempts were also made to calculate the distance from the Earth to the Sun by observing Venus. To do this, it is necessary, when the planet passes directly between the Sun and the Earth, using the parallax method, to measure insignificant differences in the start or end time of the passage at two fairly distant points of our planet. The distance between the points is further used as the length of the base for determining the distances to the Sun and Venus by triangulation.

Historians do not know when astronomers first observed the passage of the planet Venus across the disk of the Sun, but they know the name of the person who first predicted such a passage. It was the German astronomer Johannes Kepler, who predicted the passage of 1631. However, in the predicted year, due to some inaccuracy of the Keplerian forecast, no one observed the passage in Europe ...

Fig.6 Jerome Horrocks observes the passage of the planet Venus across the disk of the Sun. Source: wikipedia.org

But another astronomer - Jerome Horrocks, having refined Kepler's calculations, found out the exact periods of repetition of passages, and on December 4, 1639, from his home in Much Hoole in England, he was able to see with his own eyes the passage of Venus across the solar disk.

Using a simple telescope, Horrocks projected the solar disk onto a board where it was safe for the observer's eyes to see everything that happened against the background of the solar disk. And then at 3:15 pm, just half an hour before sunset, Horrocks finally saw the predicted passage. With the help of the observations made, the English astronomer tried to estimate the distance from the Earth to the Sun, which turned out to be 95.6 million km.

In 1667, Giovanni Domenico Cassini made the first attempt to determine the period of rotation of Venus around its axis. The value he received was very far from the actual one and amounted to 23 hours and 21 minutes. This was due to the fact that Venus had to be observed only once a day and only for a few hours. Pointing his telescope at the planet for several days and seeing the same picture all the time, Cassini came to the conclusion that the planet Venus had made a full rotation around its axis.

After the Horrocks and Cassini observations, and knowing Kepler's calculations, astronomers around the world eagerly awaited the next opportunity to observe the transit of Venus. And such an opportunity presented itself to them in 1761. Among the astronomers who conducted the observations was our Russian scientist Mikhail Vasilievich Lomonosov, who discovered when the planet entered the solar disk, as well as when leaving it, a bright ring around the dark disk of Venus. Lomonosov explained the observed phenomenon, later named after him (“the Lomonosov phenomenon”) by the presence of an atmosphere near Venus, in which the sun's rays were refracted.

After 8 years of observation, the English astronomer William Herschel and the German astronomer Johann Schroeter continued their observations, "discovering" the Venusian atmosphere for the second time.

In the 60s of the XIX century, astronomers began to make attempts to find out the composition of the discovered atmosphere of Venus, and first of all to determine the presence of oxygen and water vapor in it using spectral analysis. However, neither oxygen nor water vapor was found. Some time later, already in the twentieth century, attempts to find the "gases of life" resumed: observations and research were conducted by A. A. Belopolsky in Pulkovo (Russia) and Vesto Melvin Slifer in Flagstaff (USA).

In the same 19th century Italian astronomer Giovanni Schiaparelli again tried to establish the period of rotation of Venus around its axis. Assuming that the circulation of Venus to the Sun is always one side associated with its very slow rotation, he set the period of its rotation around the axis as equal to 225 days, which was 18 days less than the real one.

Fig. 7 Mount Wilson Observatory. Credit: MWOA

In 1923, Edison Pettit and Seth Nicholson at the Mount Wilson Observatory on Mount Wilson in California (USA) began to measure the temperature of the upper clouds of Venus, which were subsequently carried out by many scientists. Nine years later, American astronomers W. Adams and T. Denham at the same observatory recorded three bands in the spectrum of Venus belonging to carbon dioxide (CO 2 ). The intensity of the bands led to the conclusion that the amount of this gas in the Venusian atmosphere is many times greater than its content in the Earth's atmosphere. No other gases have been found in the Venusian atmosphere.

In 1955, William Sinton and John Strong (USA) measured the temperature of the cloudy layer of Venus, which turned out to be -40 ° C, and even lower near the poles of the planet.

In addition to the Americans, Soviet scientists N.P. Barabashov, V.V. Sharonov and V.I. Yezersky, French astronomer B. Lio. Their research, as well as the theory of light scattering by the dense atmospheres of planets developed by Sobolev, testified that the particle sizes of Venus clouds were about one micrometer. Scientists could only find out the nature of these particles and study in more detail the entire thickness of the cloudy layer of Venus, and not just its upper boundary. And for this it was necessary to send interplanetary stations to the planet, which were subsequently created by scientists and engineers of the USSR and the USA.

The first spacecraft launched to the planet Venus was Venera 1. This event took place on February 12, 1961. However, after some time, communication with the device was lost and Venera-1 entered the orbit of the Sun's satellite.

Fig. 8 "Venus-4". Credit: NSSDC

Fig. 9 "Venus-5". Credit: NSSDC

The next attempt was also unsuccessful: the Venera-2 apparatus flew at a distance of 24 thousand km. from the planet. Only Venera-3, launched by the Soviet Union in 1965, was able to come relatively close to the planet and even land on its surface, which was facilitated by a specially designed descent vehicle. But due to the failure of the station's control system, no data on Venus was received.

After 2 years - on June 12, 1967, Venera-4 set off for the planet, also equipped with a descent vehicle, the purpose of which was to study the physical properties and chemical composition of the Venusian atmosphere using 2 resistance thermometers, a barometric sensor, an ionization atmospheric density meter and 11 cartridges - gas analyzers. The device fulfilled its purpose by establishing the presence of a huge amount of carbon dioxide, a weak magnetic field surrounding the planet and the absence of radiation belts.

In 1969, with an interval of only 5 days, 2 interplanetary stations with serial numbers 5 and 6 went to Venus at once.

Their descent vehicles, equipped with radio transmitters, radio altimeters and other scientific equipment, transmitted information about the pressure, temperature, density and chemical composition of the atmosphere during the descent. It turned out that the pressure of the Venusian atmosphere reaches 27 atmospheres; It was not possible to find out whether it could exceed the indicated value: the descent vehicles were simply not designed for higher pressure. The temperature of the Venusian atmosphere during the descent of the vehicles ranged from 25° to 320°C. The composition of the atmosphere was dominated by carbon dioxide with a small amount of nitrogen, oxygen and an admixture of water vapor.

Fig. 10 "Mariner-2". Credit: NASA/JPL

In addition to the spacecraft of the Soviet Union, the American spacecraft of the Mariner series were engaged in the study of the planet Venus, the first of which with serial number 2 (No. 1 crashed at the start) flew past the planet in December 1962, determining the temperature of its surface. In a similar way, flying past the planet in 1967, Venus was explored by another American spacecraft, Mariner 5. Fulfilling its program, the fifth Mariner confirmed the predominance of carbon dioxide in the atmosphere of Venus, found out that the pressure in the thickness of this atmosphere can reach 100 atmospheres, and the temperature - 400 ° C.

It should be noted that the study of the planet Venus in the 60s. came from the earth. So, with the help of radar methods, American and Soviet astronomers found that the rotation of Venus is reversed, and the rotation period of Venus is ~243 days.

On December 15, 1970, the Venera-7 spacecraft reached the surface of the planet for the first time and, having worked on it for 23 minutes, transmitted data on the composition of the atmosphere, the temperature of its various layers, as well as pressure, which, according to the results of measurements, turned out to be 90 atmospheres.

A year and a half later, in July 1972, another Soviet apparatus landed on the surface of Venus.

With the help of scientific equipment installed on the descent vehicle, the illumination on the surface of Venus was measured, equal to 350 ± 150 lux (as on Earth on a cloudy day), and the density of surface rocks, equal to 1.4 g/cm 3 . It was found that the clouds of Venus lie at an altitude of 48 to 70 km, have a layered structure and consist of droplets of 80% sulfuric acid.

In February 1974, Mariner 10 flew past Venus, photographing its cloud cover for 8 days in order to study the dynamics of the atmosphere. Based on the images obtained, it was possible to determine the rotation period of the Venusian cloud layer equal to 4 days. It also turned out that this rotation occurs clockwise when viewed from the north pole of the planet.

fig.11 Venera-10 descent vehicle. Credit: NSSDC

A few months later - in October 74th, Soviet spacecraft with serial numbers 9 and 10 landed on the surface of Venus. Having landed 2200 km apart, they transmitted to Earth the first panoramas of the surface at the landing sites. For an hour, the descent vehicles transmitted scientific information from the surface to spacecraft, which were transferred to the orbits of artificial satellites of Venus and relayed it to Earth.

It should be noted that after the Vener-9 and 10 flights, the Soviet Union launched all the spacecraft of this series in pairs: first one apparatus was sent to the planet, then another with a minimum time interval.

So, in September 1978, Venera-11 and Venera-12 went to Venus. On December 25 of the same year, their descent vehicles reached the surface of the planet, while taking a number of pictures and transmitting some of them to Earth. Partly, because one of the descent vehicles did not open the protective covers of the chamber.

During the descent of the vehicles, electrical discharges were registered in the atmosphere of Venus, and extremely powerful and frequent. So, one of the devices detected 25 discharges per second, the other - about a thousand, and one of the peals of thunder lasted 15 minutes. According to astronomers, electrical discharges were associated with active volcanic activity in the places of descent of spacecraft.

Around the same time, the study of Venus was already conducted by the spacecraft of the American series - Pioneer-Venus-1, launched on May 20, 1978.

Having entered a 24-hour elliptical orbit around the planet on December 4, the device performed radar mapping of the surface for a year and a half, studied the magnetosphere, ionosphere and cloud structure of Venus.

fig.12 "Pioneer-Venus-1". Credit: NSSDC

Following the first "pioneer", the second went to Venus. It happened on August 8, 1978. On November 16, the first and largest of the descent vehicles separated from the apparatus, 4 days later 3 other descent vehicles separated. On December 9, all four modules entered the planet's atmosphere.

According to the results of the study of the Pioneer-Venera-2 descent vehicles, the composition of the atmosphere of Venus was determined, as a result of which it turned out that the content of the concentration of argon-36 and argon-38 in it is 50-500 times higher than the concentration of these gases in the Earth's atmosphere. The atmosphere is predominantly carbon dioxide, with small amounts of nitrogen and other gases. Under the very clouds of the planet, traces of water vapor and a higher than expected concentration of molecular oxygen were found.

The cloud layer itself, as it turned out, consists of at least 3 well-defined layers.

The upper one, lying at altitudes of 65-70 km, contains drops of concentrated sulfuric acid. The 2 other layers are approximately the same in composition, with the only difference being that larger sulfur particles predominate in the lowest layer. At altitudes below 30 km. Venus's atmosphere is relatively transparent.

During the descent, the devices carried out temperature measurements, which confirmed the colossal greenhouse effect that prevails on Venus. So, if at altitudes of about 100 km the temperature was -93°C, then at the upper boundary of the clouds -40°C, and then continued to increase, reaching 470°C near the surface...

In October-November 1981, with an interval of 5 days, Venera-13 and Venera-14 set off, the descent vehicles of which in March, already on the 82nd, reached the surface of the planet, transmitting to Earth panoramic images of the landing sites, on which the yellow-green Venusian sky was visible, and examining the composition of the Venusian soil, in which they found: silica (up to 50% of the total mass of the soil), aluminum alum (16%), magnesium oxides (11%), iron, calcium and others elements. In addition, with the help of a sound recording device installed on Venera-13, scientists for the first time heard the sounds of another planet, namely, thunder.

fig.13 The surface of the planet Venus. A picture of the device "Venus-13" dated March 1, 1982. Credit: NSSDC

On June 2, 1983, AMS (automatic interplanetary station) Venera-15 set off for the planet Venus, which on October 10 of the same year entered a polar orbit around the planet. On October 14, Venera-16 was launched into orbit, launched 5 days later. Both stations were designed to study the Venusian terrain using the radars installed on their board. Having worked together for more than eight months, the stations obtained an image of the planet's surface within a vast area: from the north pole to ~30° north latitude. As a result of processing these data, a detailed map of the northern hemisphere of Venus was compiled on 27 sheets and the first atlas of the planet's relief was published, which, however, covered only 25% of its surface. Also, based on the materials of the surveys of the vehicles, Soviet and American cartographers, as part of the first international project on extraterrestrial cartography, held under the auspices of the Academy of Sciences and NASA, jointly created a series of three overview maps of northern Venus. The presentation of this series of maps under the name "Magellan Flight Planning Kit" took place in the summer of 1989 at the International Geological Congress in Washington.

fig.14 Descent module AMS "Vega-2". Credit: NSSDC

After Venus, the study of the planet was continued by the Soviet AMS of the Vega series. There were two of these devices: Vega-1 and Vega-2, which, with a difference of 6 days, launched to Venus in 1984. Six months later, the vehicles came close to the planet, then the descent modules separated from them, which, having entered the atmosphere, also divided into landing modules and balloon probes.

2 balloon probes, after filling the shells of their parachutes with helium, drifted at an altitude of about 54 km in different hemispheres of the planet, and transmitted data for two days, flying a path of about 12 thousand km in this time. The average speed with which the probes flew this way was 250 km/h, which was facilitated by the powerful global rotation of the atmosphere of Venus.

The probe data showed the presence of very active processes in the cloud layer characterized by powerful updrafts and downdrafts.

When the Vega-2 probe flew in the Aphrodite region over a 5 km high peak, it hit an air pocket, dropping sharply by 1.5 km. Both probes also recorded lightning discharges.

The landers studied the cloud layer and the chemical composition of the atmosphere while descending, after which, having made a soft landing on the Mermaid Plain, they began to analyze the soil by measuring X-ray fluorescence spectra. At both points where the modules landed, they discovered rocks with relatively low contents of natural radioactive elements.

In 1990, when performing gravitational maneuvers, the Galileo (Galileo) spacecraft flew past Venus, from which a survey was made with the NIMS infrared spectrometer, as a result of which it turned out that at wavelengths of 1.1, 1.18 and 1, The 02 µm signal correlates with the topography of the surface, that is, for the corresponding frequencies there are "windows" through which the surface of the planet is visible.

Fig. 15 Loading the Magellan interplanetary station into the cargo compartment of the Atlantis spacecraft. Credit: JPL

A year earlier, on May 4, 1989, NASA's Magellan interplanetary station set off for the planet Venus, which, having worked until October 1994, obtained photographs of almost the entire surface of the planet, simultaneously performing a number of experiments.

The survey was carried out until September 1992, covering 98% of the planet's surface. Entering in August 1990 into an elongated polar orbit around Venus with altitudes from 295 to 8500 km and an orbital period of 195 minutes, the device mapped a narrow strip 17 to 28 km wide and about 70 thousand km long at each approach to the planet. In total, there were 1800 such stripes.

Since Magellan repeatedly photographed many areas from different angles, which made it possible to compile a three-dimensional model of the surface, as well as to explore possible changes in the landscape. The stereo image was obtained for 22% of the Venusian surface. In addition, a map of the heights of the surface of Venus obtained using an altimeter (altimeter) and a map of the electrical conductivity of its rocks were compiled.

According to the results of the images, in which details up to 500 m in size were easily distinguished, it was found that the surface of the planet Venus is mainly occupied by hilly plains, and is relatively young by geological standards - about 800 million years. There are relatively few meteorite craters on the surface, but traces of volcanic activity are often found.

From September 1992 to May 1993, Magellan was studying the gravitational field of Venus. During this period, he did not carry out surface radar, but broadcast a constant radio signal to the Earth. By changing the frequency of the signal, it was possible to determine the slightest changes in the speed of the device (the so-called Doppler effect), which made it possible to identify all the features of the planet's gravitational field.

In May, Magellan embarked on its first experiment: practical application of atmospheric braking technology to refine previously obtained knowledge about the gravitational field of Venus. To do this, its lower point of the orbit was slightly lowered so that the device touched the upper layers of the atmosphere and changed the parameters of the orbit without fuel consumption. In August, the Magellan orbit ran along the heights of 180-540 km, with a period of revolution of 94 minutes. Based on the results of all measurements, a "gravitational map" was compiled, covering 95% of the surface of Venus.

Finally, in September 1994, the final experiment was carried out, the purpose of which was to study the upper atmosphere. The solar panels of the apparatus were deployed like the blades of a windmill, and the Magellan's orbit was lowered. This made it possible to obtain information about the behavior of molecules in the uppermost layers of the atmosphere. On October 11, the orbit was lowered for the last time, and on October 12, when entering the dense layers of the atmosphere, communication with the spacecraft was lost.

During its operation, Magellan made several thousand orbits around Venus, taking pictures of the planet three times using side-scan radars.

Fig.16 Cylindrical map of the surface of the planet Venus, compiled from images of the Magellan interplanetary station. Credit: NASA/JPL

After the flight of the Magellan, for a long 11 years, a break reigned in the history of the study of Venus by spacecraft. The program of interplanetary research of the Soviet Union was curtailed, the Americans switched to other planets, primarily to the gas giants: Jupiter and Saturn. And only on November 9, 2005, the European Space Agency (ESA) sent to Venus a new-generation Venus Express spacecraft, created on the same platform as the Mars Express launched 2 years earlier.

fig.17 Venus Express. Credit: ESA

5 months after the launch, on April 11, 2006, the apparatus arrived at the planet Venus, soon entering a highly elongated elliptical orbit and becoming its artificial satellite. At the most distant point of the orbit from the center of the planet (apocenter), Venus Express went to a distance of 220 thousand kilometers from Venus, and at the closest point (pericenter) it passed at an altitude of only 250 kilometers from the surface of the planet.

Some time later, due to subtle orbital corrections, the periapsis of Venus Express was lowered even lower, which allowed the device to enter the uppermost layers of the atmosphere, and, due to aerodynamic friction, over and over again, slightly but surely, slowing down the height of the apoapsis. As a result, the parameters of the orbit, which became circumpolar, acquired the following parameters: the height of the apocenter - 66,000 kilometers, the height of the pericenter - 250 kilometers, the orbital period of the apparatus in orbit - 24 hours.

The parameters of the near-polar working orbit of the Venus Express were not chosen by chance: so the orbital period of 24 hours is convenient for regular communication with the Earth: approaching the planet, the device collects scientific information, and moving away from it, conducts an 8-hour communication session, transmitting up to 250 MB of information. Another important feature of the orbit is its perpendicularity to the equator of Venus, because of which the device has the ability to explore the polar regions of the planet in detail.

When entering a near-polar orbit, an unfortunate nuisance happened to the device: the PFS spectrometer, designed to study the chemical composition of the atmosphere, failed, or rather was turned off. As it turned out, the mirror was jammed, which was supposed to switch the "look" of the device from the reference source (on board the probe) to the planet. After a number of attempts to circumvent the failure, the engineers were able to rotate the mirror 30 degrees, but this was not enough for the device to work, and in the end it had to be turned off.

On April 12, the device for the first time took a picture of the south pole of Venus, which had not been photographed before. These first photographs, taken with the VIRTIS spectrometer from a height of 206,452 kilometers above the surface, revealed a dark funnel similar to a similar formation above the planet's north pole.

fig.18 Clouds over the surface of Venus. Credit: ESA

On April 24, the VMC camera took a series of images of Venus's cloud cover in the ultraviolet range, which is associated with a significant - 50% - absorption of this radiation in the planet's atmosphere. After binding to the coordinate grid, a mosaic image was obtained, covering a significant area of ​​clouds. Analysis of this image revealed low-contrast ribbon structures resulting from strong winds.

A month after arrival - on May 6 at 23:49 Moscow time (19:49 UTC), Venus Express moved into its permanent working orbit with an orbital period of 18 hours.

On May 29, the station conducted an infrared survey of the south polar region, revealing a vortex of a very unexpected shape: with two "calm zones" that are intricately connected to each other. After studying the image in more detail, the scientists came to the conclusion that in front of them are 2 different structures lying at different heights. How stable this atmospheric formation is is not yet clear.

On July 29, VIRTIS took 3 images of Venus's atmosphere, from which a mosaic was made showing its complex structure. The images were taken with an interval of about 30 minutes and already noticeably did not coincide at the boundaries, which indicates the high dynamism of the atmosphere of Venus, associated with hurricane-force winds blowing at speeds of over 100 m/s.

Another spectrometer installed on the Venus Express, SPICAV, found that clouds in the atmosphere of Venus can rise up to 90 kilometers in the form of dense fog and up to 105 kilometers, but already in the form of a more transparent haze. Previously, other spacecraft recorded clouds only up to a height of 65 kilometers above the surface.

In addition, using the SOIR block as part of the SPICAV spectrometer, scientists discovered "heavy" water in the atmosphere of Venus, which includes atoms of the heavy hydrogen isotope - deuterium. Ordinary water in the atmosphere of the planet is enough to cover its entire surface with a 3-centimeter layer.

By the way, knowing the percentage of “heavy water” to ordinary water, one can evaluate the dynamics of the water balance of Venus in the past and present. Based on these data, it was suggested that in the past, an ocean several hundred meters deep could have existed on the planet.

Another important scientific device installed on the Venera Express, the ASPERA plasma analyzer, registered the high rate of matter escape from the atmosphere of Venus, and also tracked the trajectories of other particles, in particular helium ions, of solar origin.

"Venus Express" continues to work until now, although the estimated duration of the mission of the apparatus directly on the planet was 486 Earth days. But the mission could be extended, if the station's resources allow, for the same period of time, which apparently happened.

Currently, Russia is already developing a fundamentally new spacecraft - the Venera-D interplanetary station, designed for a detailed study of the atmosphere and surface of Venus. As expected, the station will be able to work on the surface of the planet for 30 days, possibly more.

On the other side of the ocean - in the United States, by order of NASA, the Global Aerospace Corporation has also recently begun to develop a project to explore Venus using a balloon, the so-called. "Controlled Air Robot Explorer" or DARE.

It is assumed that the DARE balloon with a diameter of 10 m will fly in the cloud layer of the planet at an altitude of 55 km. DARE's altitude and direction of flight will be controlled by a stratoplane, which looks like a small aircraft.

A gondola with television cameras and several dozen small probes will be located on a cable under the balloon, which will be dropped to the surface in areas of interest for observation and study the chemical composition of various geological structures on the surface of the planet. These areas will be selected on the basis of a detailed survey of the area.

The duration of the balloon mission is from six months to a year.

Orbital motion and rotation of Venus

fig.19 Distance from the terrestrial planets to the Sun. Credit: Lunar and Planetary Institute

Around the Sun, the planet Venus moves in a close to circular orbit, inclined to the plane of the ecliptic at an angle of 3 ° 23 "39". The eccentricity of the Venusian orbit is the smallest in the solar system, and is only 0.0068. Therefore, the distance from the planet to the Sun always remains approximately the same, amounting to 108.21 million km But the distance between Venus and the Earth varies, and within a wide range: from 38 to 258 million km.

In its orbit, located between the orbits of Mercury and the Earth, the planet Venus moves at an average speed of 34.99 km / s and a sidereal period of 224.7 Earth days.

Venus rotates around its axis much more slowly than in orbit: the Earth has time to turn 243 times, and Venus - only 1. That is. the period of its rotation around its axis is 243.0183 Earth days.

Moreover, this rotation does not occur from west to east, as with all other planets, except for Uranus, but from east to west.

The reverse rotation of the planet Venus leads to the fact that the day on it lasts 58 Earth days, the night lasts the same, and the duration of the Venusian day is 116.8 Earth days, so that during the Venusian year you can see only 2 sunrises and 2 sunsets, and the sunrise will occur in the west, and the setting will occur in the east.

The rotation speed of the solid body of Venus can only be reliably determined by radar, due to the continuous cloud cover that hides its surface from the observer. The first radar reflection from Venus was obtained in 1957, and at first radio pulses were sent to Venus in order to measure the distance to refine the astronomical unit.

In the 1980s, the USA and the USSR began to study the spreading of the reflected pulse in frequency (“the spectrum of the reflected pulse”) and delay in time. Blurring in frequency is explained by the rotation of the planet (Doppler effect), delay in time - by different distances to the center and edges of the disk. These studies were carried out mainly on decimeter radio waves.

In addition to the fact that the rotation of Venus is reversed, it has another very interesting feature. The angular velocity of this rotation (2.99 10 -7 rad / sec) is just such that during the lower connection, Venus faces the Earth all the time with the same side. The reasons for this consistency between the rotation of Venus and the orbital motion of the Earth are not yet clear ...

And finally, let's say that the inclination of the plane of the equator of Venus to the plane of its orbit does not exceed 3 °, which is why the seasonal changes on the planet are insignificant, and there are no seasons at all.

The internal structure of the planet Venus

The average density of Venus is one of the highest in the solar system: 5.24 g/cm 3 , which is only 0.27 g less than the density of the Earth. The masses and volumes of both planets are also very similar, with the difference that these parameters are slightly larger for the Earth: the mass is 1.2 times, the volume is 1.15 times.

fig.20 The internal structure of the planet Venus. Credit: NASA

Based on the considered parameters of both planets, we can conclude that their internal structure is similar. And indeed: Venus, like the Earth, consists of 3 layers: crust, mantle and core.

The topmost layer is the Venusian crust, about 16 km thick. The crust consists of basalts, which have a low density - about 2.7 g / cm 3, and formed as a result of the outpouring of lava on the surface of the planet. This is probably why the Venusian crust has a relatively small geological age - about 500 million years. According to some scientists, the process of outpouring of lava flows on the surface of Venus occurs with a certain periodicity: first, the substance in the mantle, due to the decay of radioactive elements, heats up: convective flows or plumes break open the planet's crust, forming unique surface details - tesserae. Having reached a certain temperature, lava flows make their way to the surface, covering almost the entire planet with a layer of basalts. Basalt eruptions occurred repeatedly, and during periods of lull in volcanic activity, lava plains were stretched due to cooling, and then belts of Venusian cracks and ridges were formed. About 500 million years ago, the processes in the upper mantle of Venus seemed to have subsided, perhaps due to the depletion of internal heat.

Under the planetary crust lies the second layer - the mantle, which extends to a depth of about 3300 km to the border with the iron core. Apparently, the mantle of Venus consists of two layers: a solid lower mantle and a partially molten upper one.

The core of Venus, whose mass is about a quarter of the entire mass of the planet, and the density - 14 g / cm 3 - is solid or partially molten. This assumption was put forward on the basis of a study of the planet's magnetic field, which simply does not exist. And if there is no magnetic field, then there is no source that generates this magnetic field, i.e. in the iron core there is no movement of charged particles (convective flows), therefore, there is no movement of matter in the core. True, the magnetic field may not be generated due to the slow rotation of the planet ...

Surface of the planet Venus

The shape of the planet Venus is close to spherical. More precisely, it can be represented by a triaxial ellipsoid, whose polar oblateness is two orders of magnitude smaller than that of the Earth.

In the equatorial plane, the semiaxes of the Venus ellipsoid are 6052.02 ± 0.1 km and 6050.99 ± 0.14 km. The polar semiaxis is 6051.54±0.1 km. Knowing these dimensions, it is possible to calculate the surface area of ​​Venus - 460 million km 2.

fig.21 Comparison of the planets of the solar system. Credit: website

Data on the dimensions of the solid body of Venus were obtained using radio interference methods and refined using radio altimeter and trajectory measurements when the planet was within range of spacecraft.

Fig.22 Estla region on Venus. A high volcano is visible in the distance. Credit: NASA/JPL

Most of the surface of Venus is occupied by plains (up to 85% of the entire area of ​​the planet), among which smooth, slightly complicated by a network of narrow winding gently sloping ridges, basalt plains predominate. A much smaller area than smooth ones is occupied by lobed or hilly plains (up to 10% of the surface of Venus). They are characterized by tongue-like protrusions, like lobes, differing in radio brightness, which can be interpreted as extensive lava covers of low-viscosity basalts, as well as numerous cones and domes 5-10 km in diameter, sometimes with craters on top. There are also areas of plains on Venus, densely covered with cracks or practically not disturbed by tectonic deformations.

pic.23 Ishtar archipelago. Credit: NASA/JPL/USGS

In addition to the plains on the surface of Venus, three vast elevated areas have been discovered, which are named after the earthly goddesses of love.

One such area, the Ishtar archipelago, is a vast mountainous region in the northern hemisphere, comparable in size to Australia. In the center of the archipelago lies the Lakshmi plateau of volcanic origin, which is twice the size of terrestrial Tibet. From the west, the plateau is bounded by the Akny mountains, from the northwest - by the Freya mountains, up to 7 km high, and from the south - by the Danu folded mountains and Vesta and Ut ledges, with a total decrease of up to 3 km or more. The eastern part of the plateau "cuts" into the highest mountain system of Venus - the Maxwell Mountains, named after the English physicist James Maxwell. The central part of the mountain range rises to 7 km, and individual mountain peaks located near the zero meridian (63 ° N and 2.5 ° E) rise to heights of 10.81-11.6 km, 15 km above the deep Venusian trench, which lies near the equator.

Another elevated area - the archipelago of Aphrodite, stretching along the Venusian equator, is even larger in size: 41 million km 2, although the heights are lower here.

This vast territory, located in the equatorial region of Venus and stretching for 18 thousand km, covers longitudes from 60 ° to 210 °. It extends from 10°N. up to 45°S more than 5 thousand km, and its eastern tip - the region of Atla - stretches up to 30 ° north latitude.

The third elevated region of Venus is the land of Lada, which lies in the southern hemisphere of the planet and is opposite the Ishtar archipelago. This is a fairly flat area, the average surface height of which is close to 1 km, and the maximum (slightly more than 3 km) is reached in the crown of Quetzalpetlatl with a diameter of 780 km.

Fig. 24 Tessera Ba "het. Credit: NASA / JPL

In addition to these elevated regions, because of their size and height, called "lands", other less extensive ones stand out on the surface of Venus. Such, for example, as tesserae (from Greek - tiles), which are hills or highlands ranging in size from hundreds to thousands of kilometers, the surface of which is crossed in different directions by systems of stepped ridges and trenches separating them, formed by swarms of tectonic faults.

Ridges or ridges within tesserae can be linear and extended: up to many hundreds of kilometers. And they can be sharp or, conversely, rounded, sometimes with a flat top surface limited by vertical ledges, which resembles a combination of ribbon grabens and horsts in terrestrial conditions. Quite often, the ridges resemble a wrinkled film of frozen kissel or rope lavas of the basalts of the Hawaiian Islands. The height of the ridge can be up to 2 km, and the ledges - up to 1 km.

The trenches separating the ridges go far beyond the uplands, stretching for thousands of kilometers across the vast Venusian plains. In topography and morphology, they are similar to the rift zones of the Earth and seem to be of the same nature.

The formation of the tesserae themselves is associated with repeated tectonic movements of the upper layers of Venus, accompanied by compression, tension, splits, uplifts and subsidence of various parts of the surface.

These, it must be said, are the most ancient geological formations on the surface of the planet, therefore they have been given the appropriate names: in honor of the goddesses associated with time and fate. Thus, a large upland, stretching for 3,000 km near the north pole, is called the tessera of Fortune, to the south of it is the Laima tessera, which bears the name of the Latvian goddess of happiness and fate.

Together with lands or continents, tesserae occupy a little more than 8.3% of the planet's territory, i.e. exactly 10 times smaller area than the plains, and possibly are the foundation of a significant, if not all, territory of the plains. The remaining 12% of the territory of Venus is occupied by 10 types of relief: crowns, tectonic faults and canyons, volcanic domes, "arachnoids", mysterious channels (furrows, lines), ridges, craters, paters, craters with dark parabolas, hills. Let's consider each of these elements of the relief in more detail.

Fig.25 The crown is a unique relief detail on Venus. Credit: NASA/JPL

The crowns, which are on a par with tesserae, are unique details of the relief of the surface of Venus, they are large oval or round volcanic depressions with an elevated central part, surrounded by ramparts, ridges, depressions. The central part of the crowns is occupied by a vast intermountain plateau, from which mountain ranges extend in rings, often rising above the central part of the plateau. The ring framing of the crowns is usually incomplete.

Crowns on the planet Venus, according to the results of research from spacecraft, found several hundred. The crowns differ among themselves in size (from 100 to 1000 km), and in the age of the rocks that compose them.

Crowns were formed, apparently, as a result of active convective flows in the mantle of Venus. Around many of the crowns, solidified lava flows are observed, diverging to the sides in the form of wide tongues with a scalloped outer edge. Apparently, it was the crowns that could serve as the main sources through which molten matter from the depths entered the planet's surface, solidifying to form vast flat areas occupying up to 80% of the territory of Venus. The names of these abundant sources of molten rocks are given by the names of the goddesses of fertility, harvest, flowers.

Some scientists believe that the crowns are preceded by another specific form of Venusian relief - arachnoids. Arachnoids, which got their name because of their resemblance to spiders, resemble crowns in shape, but are smaller. The bright lines extending from their centers for many kilometers may correspond to cracks in the surface that arose when magma erupted from the bowels of the planet. In total, about 250 arachnoids are known.

In addition to tesserae, crowns and arachnoids, the formation of tectonic faults or trenches is associated with endogenous (internal) processes. Tectonic faults are often grouped into long (up to thousands of kilometers) belts that are very widespread on the surface of Venus and can be associated with other structural landforms, for example, with canyons, which in their structure resemble terrestrial continental rifts. In some cases, an almost orthogonal (rectangular) pattern of mutually intersecting cracks is observed.

Fig. 27 Mount Maat. Credit: JPL

Volcanoes are also very widespread on the surface of Venus: there are thousands of them. Moreover, some of them reach enormous sizes: up to 6 km in height and 500 km in width. But most of the volcanoes are much smaller: only 2-3 km in diameter and 100 m in height. The vast majority of Venusian volcanoes are extinct, but some may be erupting at the present time. The most obvious candidate for an active volcano is Mount Maat.

In a number of places on the surface of Venus, mysterious furrows and lines from hundreds to several thousand kilometers long and 2 to 15 kilometers wide have been discovered. Outwardly, they look like river valleys and have the same features: meander-like convolutions, divergence and convergence of individual "ducts", and, in rare cases, something similar to a delta.

The longest channel on the planet Venus is the Baltis valley, about 7000 km long with a very consistent (2-3 km) width.

By the way, the northern part of the Baltis valley was also discovered on the images of the Venera-15 and Venera-16 satellites, but the resolution of the images of that time was not high enough to distinguish the details of this formation, and it was mapped as an extended crack of unknown origin.

fig.28 Channels on Venus within the boundaries of the land of Lada. Credit: NASA/JPL

The origin of the Venusian valleys or channels remains a mystery, primarily because scientists do not know of a liquid that can cut through the surface at such distances. Calculations made by scientists have shown that basaltic lavas, traces of which are widespread on the entire surface of the planet, would not have enough heat reserves to continuously flow and melt the substance of the basalt plains, cut channels in them for thousands of kilometers. After all, such channels are known, for example, on the Moon, although their length is only tens of kilometers.

Therefore, it is likely that the liquid that cut through the basaltic plains of Venus for hundreds and thousands of kilometers could be superheated komatiite lavas or even more exotic liquids like molten carbonates or molten sulfur. Until the end, the origin of the valleys of Venus is unknown ...

In addition to the valleys, which are negative landforms, positive landforms are also common on the plains of Venus - ridges, also known as one of the components of the specific tessera relief. Ridges often form into extended (up to 2000 km or more) belts a few hundred kilometers wide. The width of an individual ridge is much smaller: rarely up to 10 km, and on the plains it is reduced to 1 km. The heights of the ridges are from 1.0-1.5 to 2 km, and the ledges limiting them are up to 1 km. Light winding ridges against the background of a darker radio image of the plains are the most characteristic pattern of the surface of Venus and occupy ~ 70% of its area.

The ridges are very similar to such details of the surface of Venus as hills, with the difference that their sizes are smaller.

All the forms (or types) of the surface relief of Venus described above owe their origin to the internal energy of the planet. There are only three types of relief, the origin of which is caused by external causes, on Venus: craters, paters and craters with dark parabolas.

Unlike many other bodies of the solar system: terrestrial planets, asteroids, relatively few meteorite impact craters have been found on Venus, which is associated with active tectonic activity, which ceased 300-500 million years ago. Volcanic activity proceeded very rapidly, since otherwise the number of craters in older and younger areas would have differed markedly and their distribution over the area would not have been random.

A total of 967 craters have been discovered on the surface of Venus to date, ranging in diameter from 2 to 275 km (near the Mead crater). Craters are conditionally divided into large (over 30 km) and small (less than 30 km), which include 80% of the total number of all craters.

The density of impact craters on the surface of Venus is very low: about 200 times less than on the Moon, and 100 times less than on Mars, which corresponds to only 2 craters per 1 million km 2 of the Venusian surface.

Looking at the images of the planet's surface taken by the Magellan apparatus, scientists were able to see some aspects of the formation of impact craters in the conditions of Venus. Around the craters, light rays and rings were discovered - rock thrown out during the explosion. In many craters, part of the ejecta is a liquid substance, which forms, usually directed in one direction from the crater, extensive flows tens of kilometers long. So far, scientists have not yet figured out what kind of liquid it is: a superheated impact melt or a suspension of fine-grained solid matter and melt droplets suspended in the near-surface atmosphere.

Several Venusian craters are flooded with lava from the adjacent plains, but the vast majority of them have a very distinct appearance, indicating a weak intensity of material erosion processes on the surface of Venus.

The floor of most craters on Venus is dark, indicating a smooth surface.

Another common type of terrain is craters with dark parabolas, and the main area is occupied by dark (in the radio image) parabolas, the total area of ​​​​which is almost 6% of the entire surface of Venus. The color of parabolas is due to the fact that they are composed of a cover of fine-grained material up to 1-2 m thick, formed due to emissions from impact craters. It is also possible that this material was reworked by eolian processes, which dominated in a number of regions of Venus, leaving many kilometers of striped eolian relief.

Paters are similar to craters and craters with dark parabolas - craters of irregular shape or complex craters with scalloped edges.

All of these data were collected when the planet Venus was within the reach of spacecraft (Soviet, the Venera series, and American, the Mariner and Pioneer-Venus series).

So, in October 1975, the Venera-9 and Venera-10 descent vehicles made a soft landing on the surface of the planet and transmitted images of the landing site to Earth. These were the first photographs in the world transmitted from the surface of another planet. The image was obtained in visible rays using a telephotometer - a system that, according to the principle of operation, resembles a mechanical television.

In addition to photographing the surface of the Venera-8, Venera-9 and Venera-10 AMSs, they measured the density of surface rocks and the content of natural radioactive elements in them.

At the landing sites of Venera-9 and Venera-10, the density of surface rocks was close to 2.8 g/cm igneous rocks of the earth's crust...

In 1978, the American Pioneer-Venus apparatus was launched, the result of which was a topographic map created on the basis of a radar survey.

Finally, in 1983, the Venera-15 and Venera-16 spacecraft entered orbit around Venus. Using radar, they mapped the northern hemisphere of the planet up to the 30° parallel at a scale of 1:5,000,000 and for the first time discovered such unique features of the surface of Venus as tesserae and crowns.

Even more detailed maps of the entire surface with details up to 120 m in size were obtained in 1990 by the Magellan ship. With the help of computers, radar information was turned into photograph-like images showing volcanoes, mountains and other landscape details.

Fig. 30 Topographic map of Venus, compiled from images of the Magellan interplanetary station. Credit: NASA

According to the decision of the International Astronomical Union, only female names are on the map of Venus, since she herself, the only planet, bears a female name. There are only 3 exceptions to this rule: Maxwell mountains, Alpha and Beta regions.

The names for the details of its relief, which are taken from the mythologies of various peoples of the world, are assigned in accordance with the established procedure. Like this:

Hills are named after goddesses, titanides, giantesses. For example, the Ulfrun region, named after one of the nine giantesses in Scandinavian myths.

Lowlands - the heroines of myths. In honor of one of these heroines of ancient Greek mythology, the deepest lowland of Atalanta, which lies in the northern latitudes of Venus, is named.

Furrows and lines are named after female warlike mythological characters.

Crowns in honor of the goddesses of fertility, agriculture. Although the most famous of them - Pavlova's crown with a diameter of about 350 km, is named after a Russian ballerina.

The ridges are named after the goddesses of the sky, female mythological characters associated with the sky, light. So along one of the plains stretched the ridges of the Witch. And the Beregini plain from the northwest to the southeast is crossed by the ridges of Hera.

The lands and plateaus bear the names of the goddesses of love and beauty. So, one of the continents (lands) of Venus is called the land of Ishtar and is a high-mountainous region with a vast Lakshmi plateau of volcanic origin.

The canyons on Venus are named after mythological figures associated with the forest, hunting or the Moon (similar to the Roman Artemis).

The mountainous area in the northern hemisphere of the planet is crossed by the long canyon of Baba Yaga. Within the regions of Beta and Phoebe, the Devana Canyon stands out. And from the region of Themis to the land of Aphrodite, the largest Venusian quarry Parnge stretches for more than 10 thousand km.

Large craters are named after famous women. Small craters are just ordinary female names. So, on the high-mountainous plateau of Lakshmi, you can find small craters Berta, Lyudmila and Tamara, located south of the Freya mountains and east of the large Osipenko crater. Near the crown of Nefertiti is the Potanin crater, named after the Russian explorer of Central Asia, and next to it is the Voynich crater (English writer, author of the novel "The Gadfly"). And the largest crater on the planet was named after the American ethnographer and anthropologist Margaret Mead.

Paters are named according to the same principle as large craters, i.e. by the names of famous women. Example: Father Salfo.

The plains are named after the heroines of various myths. For example, the plains of the Snow Maiden and Baba Yaga. Around the North Pole stretch the Louhi plain - the mistress of the North in Karelian and Finnish myths.

Tessers are named after the goddesses of fate, happiness, good luck. For example, the largest of the Venusian tesserae is called the Tellurian tesserae.

Ledges - in honor of the goddesses of the hearth: Vesta, Ut, etc.

I must say that the planet leads in the number of named parts among all planetary bodies. On Venus, and the largest variety of names for their origin. Here are the names from the myths of 192 different nationalities and ethnic groups from all continents of the world. Moreover, the names are interspersed around the planet, without the formation of "national regions".

And in conclusion of the description of the surface of Venus, we give a brief structure of the modern map of the planet.

Back in the mid-60s, the meridian was taken as the zero meridian (corresponds to the Earth's Greenwich Meridian) on the map of Venus, passing through the center of a bright (on radar images) rounded area with a diameter of 2 thousand km, located in the southern hemisphere of the planet and called the Alpha region by the initial letter of the Greek alphabet. Later, with increasing resolution of these images, the position of the prime meridian was shifted by about 400 km due to the fact that it passed through a small bright spot in the center of a large ring structure 330 km across called Eve. After the creation of the first extensive maps of Venus in 1984, it was found that exactly on the zero meridian, in the northern hemisphere of the planet, there is a small crater with a diameter of 28 km. The crater was named Ariadne, after the name of the heroine of the Greek myth and was much more convenient as a reference point.

The zero meridian, together with the 180° meridian, divides the surface of Venus into 2 hemispheres: eastern and western.

Atmosphere of Venus. Physical conditions on the planet Venus

Above the lifeless surface of Venus lies a unique atmosphere, the densest in the solar system, discovered in 1761 by M.V. Lomonosov, who observed the passage of the planet across the solar disk.

Fig. 31 Venus covered by clouds. Credit: NASA

The atmosphere of Venus is so dense that it is absolutely impossible to see any details on the surface of the planet through it. Therefore, for a long time, many researchers believed that conditions on Venus were close to those on Earth during the Carboniferous period, and, consequently, similar fauna also lives there. However, studies carried out with the help of descent vehicles of interplanetary stations showed that the climate of Venus and the climate of the Earth are two big differences and there is nothing in common between them. So, if the temperature of the lower air layer on Earth rarely exceeds +57°C, then on Venus the temperature of the near-surface air layer reaches 480°C, and its daily fluctuations are insignificant.

Significant differences are also observed in the composition of the atmospheres of the two planets. If in the Earth's atmosphere the predominant gas is nitrogen, with a sufficient content of oxygen, an insignificant content of carbon dioxide and other gases, then in the atmosphere of Venus the situation is exactly the opposite. The predominant share of the atmosphere is carbon dioxide (~97%) and nitrogen (about 3%), with small additions of water vapor (0.05%), oxygen (thousandths of a percent), argon, neon, helium and krypton. In very small quantities there are also impurities SO, SO 2, H 2 S, CO, HCl, HF, CH 4, NH 3.

The pressure and density of the atmospheres of both planets also differ greatly. For example, the atmospheric pressure on Venus is about 93 atmospheres (93 times greater than on Earth), and the density of the Venusian atmosphere is almost two orders of magnitude higher than the density of the Earth's atmosphere and only 10 times less than the density of water. Such a high density cannot but affect the total mass of the atmosphere, which is approximately 93 times the mass of the Earth's atmosphere.

As many astronomers now believe; high surface temperature, high atmospheric pressure, and a high relative content of carbon dioxide are apparently related factors. High temperature promotes the transformation of carbonate rocks into silicate, with the release of CO 2 . On Earth, CO 2 binds and passes into sedimentary rocks as a result of the action of the biosphere, which is absent on Venus. On the other hand, a high content of CO 2 contributes to the heating of the Venusian surface and the lower layers of the atmosphere, which was established by the American scientist Carl Sagan.

In fact, the gaseous shell of the planet Venus is a giant greenhouse. It is able to let in solar heat, but does not let it out, simultaneously absorbing the radiation of the planet itself. The absorbers are carbon dioxide and water vapour. The greenhouse effect also occurs in the atmospheres of other planets. But if in the atmosphere of Mars it raises the average temperature at the surface by 9°, in the atmosphere of the Earth - by 35°, then in the atmosphere of Venus this effect reaches 400 degrees!

Some scientists believe that 4 billion years ago, the atmosphere of Venus was more like the atmosphere of the Earth with liquid water on the surface, and it was the evaporation of this water that caused the uncontrolled greenhouse effect that is still observed today...

The atmosphere of Venus consists of several layers that differ greatly in density, temperature, and pressure: the troposphere, mesosphere, thermosphere, and exosphere.

The troposphere is the lowest and densest layer of the Venusian atmosphere. It contains 99% of the mass of the entire atmosphere of Venus, of which 90% - up to a height of 28 km.

The temperature and pressure in the troposphere decrease with height, reaching at altitudes close to 50-54 km, values ​​of +20° +37°C and a pressure of only 1 atmosphere. Under such conditions, water can exist in liquid form (in the form of tiny droplets), which, together with the optimal temperature and pressure, similar to those near the surface of the Earth, creates favorable conditions for life.

The upper limit of the troposphere lies at an altitude of 65 km. above the surface of the planet, separating from the layer above - the mesosphere - tropopause. Hurricane winds prevail here with speeds of 150 m/s and higher, against 1 m/s near the surface.

Winds in the atmosphere of Venus are created by convection: hot air above the equator rises and spreads towards the poles. This global rotation is called the Hadley rotation.

fig.32 Polar vortex near the south pole of Venus. Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Univ. of Oxford

At latitudes close to 60°, Hadley's rotation stops: hot air descends and begins to move back towards the equator, which is facilitated by the high concentration of carbon monoxide in these places. However, the rotation of the atmosphere does not stop even north of the 60th latitudes: here the so-called. "polar collars". They are characterized by low temperatures, high position of clouds (up to 72 km.).

Their existence is a consequence of a sharp rise in air, as a result of which adiabatic cooling is observed.

Around the very poles of the planet, framed by "polar collars", giant polar vortices operate, four times larger than their terrestrial counterparts. Each vortex has two eyes - centers of rotation, which are called polar dipoles. The eddies rotate with a period of about 3 days in the direction of the general rotation of the atmosphere, and the wind speeds range from 35-50 m/s near their outer edges to zero at the poles.

Polar vortices, as astronomers today believe, are anticyclones with descending air currents in the center and rising sharply near the polar collars. Similar to the polar vortices of Venus, structures on Earth are winter polar anticyclones, especially the one that forms over Antarctica.

The mesosphere of Venus extends at altitudes from 65 to 120 km and can be divided into 2 layers: the first lies at an altitude of 62-73 km, has a constant temperature and is the upper boundary of the clouds; the second is at an altitude between 73-95 km, the temperature here drops with height, reaching its minimum at the upper limit of -108°C. Above 95 km above the surface of Venus, the mesopause begins - the boundary between the mesosphere and the thermosphere lying above. Within the mesopause, the temperature increases with height, reaching +27° +127°C on the day side of Venus. On the night side of Venus, within the mesopause, a significant cooling occurs and the temperature drops to -173°C. This region, the coldest on Venus, is sometimes even called the cryosphere.

At altitudes above 120 km lies the thermosphere, which extends to an altitude of 220-350 km, to the border with the exosphere - the region where light gases leave the atmosphere and there is mainly only hydrogen. The exosphere ends, and with it the atmosphere, at an altitude of ~5500 km, where the temperature reaches 600-800 K.

Within the meso- and thermosphere of Venus, as well as in the lower troposphere, the air mass rotates. True, the movement of the air mass does not occur in the direction from the equator to the poles, but in the direction from the day side of Venus to the night side. On the day side of the planet, a powerful rise of warm air occurs, which spreads at altitudes of 90-150 km, moving to the night side of the planet, where the heated air drops sharply down, resulting in adiabatic heating of the air. The temperature in this layer is only -43°C, which is as much as 130° higher than in general on the night side of the mesosphere.

Data on the characteristics and composition of the Venusian atmosphere were also obtained by AMS of the Venus series with serial numbers 4, 5 and 6. Venera 9 and 10 clarified the water vapor content in the deep layers of the atmosphere, finding out that max water vapor is contained at altitudes of 50 km , where it is a hundred times greater than that of a solid surface, and the proportion of vapor approaches one percent.

In addition to studying the composition of the atmosphere, the interplanetary stations Venera-4, 7, 8, 9, 10 measured the pressure, temperature and density in the lower layers of the atmosphere of Venus. As a result, it was found that the temperature on the surface of Venus is about 750 ° K (480 ° C), and the pressure is close to 100 atm.

The descent vehicles Venera-9 and Venera-10 also received information regarding the structure of the cloud layer. So, at altitudes from 70 to 105 km there is a rarefied stratospheric haze. Below, at an altitude of 50 to 65 km (rarely up to 90 km), there is the densest layer of clouds, which, in terms of its optical properties, is closer to rarefied fog than to clouds in the earthly sense of the word. The range of visibility here reaches several kilometers.

Under the main cloud layer - at altitudes from 50 to 35 km, the density drops several times, and the atmosphere attenuates solar radiation mainly due to Rayleigh scattering in CO 2 .

Undercloud haze appears only at night, spreading down to a level of 37 km - by midnight and up to 30 km - by dawn. By noon this haze dissipates.

fig.33 Lightning in the atmosphere of Venus. Credit: ESA

The color of the clouds of Venus is orange-yellow, due to the significant content of CO 2 in the atmosphere of the planet, large molecules of which scatter this particular part of the sunlight, and the composition of the clouds themselves, consisting of 75-80 percent sulfuric acid (perhaps even sulfuric fluoride ) with impurities of hydrochloric and hydrofluoric acids. The composition of the clouds of Venus was discovered in 1972 by American researchers Louise and Andrew Young, as well as Godfrey Sill, independently of each other.

Studies have shown that the acid in the Venusian clouds is formed chemically from sulfur dioxide (SO 2 ), which can be sources of sulfur-bearing surface rocks (pyrites) and volcanic eruptions. Volcanoes also manifest themselves in another way: their eruptions generate powerful electrical discharges - real thunderstorms in the atmosphere of Venus, which have been repeatedly recorded by the instruments of the stations of the Venus series. Moreover, thunderstorms on the planet Venus are very strong: lightning strikes 2 orders of magnitude more often than in the Earth's atmosphere. This phenomenon is called the "Electric Dragon of Venus".

The clouds are very bright, reflecting 76% of the light (this is comparable to the reflectivity of cumulus clouds in the atmosphere and polar ice caps on the Earth's surface). In other words, more than three-fourths of solar radiation is reflected by clouds and only less than one-quarter passes down.

Cloud temperature - from +10° to -40°С.

The cloud layer is rapidly moving from east to west, making one revolution around the planet in 4 Earth days (according to Mariner-10 observations).

Magnetic field of Venus. The magnetosphere of the planet Venus

The magnetic field of Venus is insignificant - its magnetic dipole moment is less than that of the Earth by at least five orders of magnitude. The reasons for such a weak magnetic field are: the slow rotation of the planet around its axis, the low viscosity of the planetary core, there may be other reasons. Nevertheless, as a result of the interaction of the interplanetary magnetic field with the ionosphere of Venus, magnetic fields of small intensity (15-20 nT), chaotically located and unstable, are created in the latter. This is the so-called induced magnetosphere of Venus, which has a bow shock, a magnetosheath, a magnetopause, and a magnetotail.

The bow shock wave lies at altitudes of 1900 km above the surface of the planet Venus. This distance was measured in 2007 during the minimum of solar activity. During maximum solar activity, the height of the shock wave increases.

The magnetopause is located at an altitude of 300 km, which is slightly higher than the ionopause. Between them there is a magnetic barrier - a sharp increase in the magnetic field (up to 40 T), which prevents the penetration of solar plasma into the depths of the atmosphere of Venus, at least during a minimum of solar activity. In the upper layers of the atmosphere, significant losses of O+, H+, and OH+ ions are associated with the activity of the solar wind. The length of the magnetopause is up to ten radii of the planet. The very same magnetic field of Venus, or rather its tail, extends to several tens of Venusian diameters.

The ionosphere of the planet, with which the presence of the magnetic field of Venus is associated, arises under the influence of significant tidal influences due to the relative proximity to the Sun, due to which an electric field is formed above the surface of Venus, the strength of which can be twice the strength of the "clear weather field" observed above the Earth's surface . The ionosphere of Venus is located at altitudes of 120-300 km and consists of three layers: between 120-130 km, between 140-160 km and between 200-250 km. At altitudes close to 180 km there may be an additional layer. The maximum number of electrons per unit volume - 3×10 11 m -3 was found in the 2nd layer near the sunflower point.

Venus comes closer to Earth than any other planet. But the dense, cloudy atmosphere does not allow you to directly see its surface. Radar images show a very wide variety of craters, volcanoes and mountains.
Surface temperatures are hot enough to melt lead, and this planet may have once had extensive oceans.

Venus is the second planet from the Sun, which has an almost circular orbit, which it bypasses in 225 Earth days at a distance of 108 million km from the Sun. Rotation around the axis of Venus takes 243 Earth days - the maximum time among all the planets. Venus rotates around its axis in the opposite direction, that is, in the opposite direction to its orbit. This slow and reverse rotation means that, as seen from Venus, the Sun rises and sets only twice a year, since the Venusian days are equal to 117 of ours. Venus approaches the Earth at a distance of 45 million km - closer than any other planet.

Venus is only slightly smaller than Earth, and has almost the same mass. For these reasons, Venus is sometimes referred to as Earth's twin or sister. However, the surface and atmosphere of these two planets are completely different. The Earth has rivers, lakes, oceans and the atmosphere we breathe. Venus is a scaldingly hot planet with a dense atmosphere that would be fatal to humans.

Before the start of the space age, astronomers knew very little about Venus. Dense clouds prevented them from seeing the surface through telescopes. The spacecraft managed to pass through the atmosphere of Venus, which consists mainly of carbon dioxide with impurities of nitrogen and oxygen. Pale yellow clouds in the atmosphere contain droplets of sulfuric acid that fall on the surface as acid rain.

Finding Venus in the sky is easier than any other planet. Its dense clouds perfectly reflect sunlight, making the planet bright. Since the orbit of Venus is closer to the Sun than the Earth's, Venus never moves far from the Sun in our sky. Every seven months, for several weeks, Venus is the brightest object in the western sky in the evening. It is called the "evening star". During these periods, the sawn brilliance of Venus is 20 times greater than the brilliance of Sirius, the brightest star in the northern sky. Three and a half months later, Venus rises three hours before the Sun, becoming the brilliant "morning star" of the eastern sky.

You can observe Venus about an hour after sunset or an hour before sunrise. The angle between Venus and the Sun never exceeds 47°. For two or three weeks near these points, Venus cannot be missed, unless the sky is clear. If you first see Venus in the pre-dawn sky during the period of greatest western elongation, then you will be able to distinguish it later, even after sunrise, it is so bright. If you use binoculars or a telescope, take the necessary precautions so that the Sun does not accidentally enter your field of vision.

It is easy to see that Venus, like Lupe, has phases. At its points of greatest elongation, the planet looks like a tiny moon in its half-disk phase. As Venus approaches the Earth, its apparent size increases slightly every day, and its shape gradually changes to a narrow crescent. But no features of the planet's surface can be seen due to dense clouds.

Transit of Venus across the disk of the Sun

It is very rare for Venus to pass exactly between the Earth and the Sun. These passages were used in the 18th century. to determine the size of the solar system. Noting the difference in time between the beginning and end of the passage when observed from different points on the Earth, astronomers estimated the distance between the Earth and Venus. Captain Cook's third voyage in search of discovery (1776-1779) included observing the passage. Venus will next cross the solar disk in 2004.

Phases of Venus

Galileo was the first to observe the phases of Venus in 1610. From the similarity with the phases of the Moon, he concluded that the orbit of Venus is closer to the Sun than the orbit of the Earth. His observations of Venus proved that the Sun is at the center of our solar system. By observing the phases of Venus once every few days for about a month, you can calculate whether this planet is approaching us or moving away from us.

hot world

The atmosphere of Venus is extremely hot and dry. The surface temperature reaches its maximum at about 480°C. The atmosphere of Venus contains 105 times more gas than the atmosphere of Earth. The pressure of this atmosphere near the surface is very high, 95 times higher than on Earth. Spaceships have to be designed to withstand the crushing, crushing force of the atmosphere. In 1970, the first spacecraft to land on Venus could only endure the sweltering heat for about one hour, just long enough to send back data on surface conditions to Earth. Russian aircraft that landed on Venus in 1982 also sent color photographs of sharp rocks to Earth.

Due to the greenhouse effect, Venus is terribly hot. The atmosphere, which is a denser blanket of carbon dioxide, retains the heat that comes from the Sun. As a result, such an amount of thermal energy accumulates that the temperature of the atmosphere is much higher than in an oven.

On Earth, where the amount of carbon dioxide and the atmosphere is small, the natural greenhouse effect raises the global temperature by 30 "C. And on Venus, the greenhouse effect raises the temperature by another 400". Studying the physical consequences of the strongest greenhouse effect on Venus, we can imagine the results that the accumulation of excess heat on the Earth, caused by the growing concentration of carbon dioxide in the atmosphere due to the burning of fossil fuels - coal and oil, can lead to.

Venus and Earth in ancient times

4.5 billion years ago, when the Earth first formed, it also had a very dense atmosphere of carbon dioxide - just like Venus. This gas, however, dissolves in water. Earth was not as hot as Venus because it is farther away from the Sun; as a result, rains washed carbon dioxide out of the atmosphere and sent it to the oceans. From the shells and bones of marine animals, rocks such as chalk and limestone arose, which included carbon and oxygen. In addition, carbon dioxide was extracted from the atmosphere of our planet and during the formation of coal and oil. There is not a lot of hearth in the atmosphere of Venus. And due to the greenhouse effect, the temperature of the atmosphere exceeds the boiling point of water up to an altitude of about 50 km. Venus may have once had oceans, but if there were, they have long since boiled away.

Surface of Venus

To study the nature of the surface of Venus under a thick layer of clouds, astronomers use both interplanetary ships and radio waves. More than 20 US and Russian spacecraft have already been heading to Venus, more than any other planet. The first Russian ship was crushed by the atmosphere. However, in the late 1970s and early 1980s, the first photographs were taken, in which formations of hard rocks are visible - sharp, sloping, crumbling, small crumbs and dust. - the chemical composition of which was similar to the volcanic rocks of the Earth.

In 1961, scientists sent radio waves to Venus and received a reflected signal on Earth, measuring the speed of the planet's rotation around its axis. In 1983, the Veiera-15 and Venera-16 spacecraft entered orbit around Venus.

Using radar, they built a map of the northern hemisphere of the planet up to parallel 30". Even more detailed maps of the entire surface with details up to 120 m in size were obtained in 1990 by the Magellan spacecraft. With the help of computers, radar information was turned into images similar to photographs, where volcanoes, mountains and other details of the landscape are visible.

impact craters

Magellan transmitted to Earth beautiful images of the huge Venusian craters. They arose as a result of impacts of giant meteorites that broke through the atmosphere of Venus to its surface. Such collisions released the liquid lava contained within the planet. Some meteorites exploded in the lower atmosphere, creating shock waves that formed dark round craters. Meteorites passing through the atmosphere fly at a speed of about 60,000 km/h. When such a meteorite hits the surface, solid rock instantly turns into hot steam, leaving a crater in the ground. Sometimes lava after such an impact finds its way up and flows out of the crater.

Volcanoes and lava

The surface of Vpori is covered with hundreds of thousands of volcanoes. There are several very large ones: 3 km high and 500 km wide. But most of the volcanoes are 2-3 km across and about 100 m high. The outpouring of lava on Venus takes much longer than on Earth. Venus is too hot for ice, rain or storms, so there is no significant weathering. This means that volcanoes and craters have not changed much since they formed millions of years ago. In the photographs of Venus taken from the Magellan, we see such an ancient landscape as you will not see on Earth - and yet it is younger than on many other planets and magnifiers.

Apparently, Venus is covered with solid rocks. Hot lava circulates beneath them, causing tension in the boggy surface layer. Lava is constantly erupting from holes and fissures in solid rock. In addition, volcanoes all the time emit streams of small droplets of sulfuric acid. In some places, thick lava, gradually oozing, accumulates in the form of huge puddles up to 25 km wide. In other places, huge paw bubbles form domes on the surface, which then fall off.

On Earth, it is not easy for geologists to find out the historian) of our planet, because the floor is constantly eroded by wind and rain. Venus is of great interest to scientists for the reason that its surface is similar to ancient fossil layers. The details of its landscape, discovered by Magellan, are hundreds of millions of years old.

Volcanoes and lava flows are preserved in an unchanging saw on this dry planet, the world of which is the closest to ours.

How to find the "morning star"

The planet rotates closer to the Sun than the Earth, so explain how to find Venus in the sky? It's pretty easy. It will always be close enough to the Sun.

Venus revolves around the Sun faster than the Earth, so it will appear in the sky in the west in the evening or before sunrise in the east.

How to Catch the Morning Star

To accurately determine the location of Venus, you can use programs - planetariums, which allow you to know its location very accurately. There are a few things to keep in mind when observing. First, you need to take into account that there is a plane of the ecliptic.

If you trace the path of the star across the sky, the line of its movement is called the ecliptic.

The ecliptic changes slightly throughout the year. In fact, it rises and falls. The highest point occurs on the day of the summer solstice, and the lowest point occurs six months later, on the day of the winter solstice. Therefore, the position of the objects of observation will always change, depending on the season.

The apparent movement of objects in the sky, due to the rotation of the Earth, is 15 degrees per hour.

Venus is not visible against sunlight until it is 5 degrees away from the Sun, so it cannot be observed for 20 minutes after sunset or before sunrise.

At its greatest east and west elongation, it moves from 45 to 47 degrees from the Sun and moves 3 hours 8 minutes ahead or behind it.

Now you know how to find a planet in the sky and you need a telescope to see more than just a bright star in the sky. In addition, a planetary filter and an auto-tracking telescope are in order so that you can focus all your attention on observing.

Good luck on your quest for the morning star.

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It is said that Napoleon was quite annoyed and angry when, one afternoon, during his trip to the Luxembourg Palace, the audience no longer looked at him, but at a star shining brightly in the daytime sky. This wonderful "star" was planet Venus.

This really does happen. It is known that in 1750, and also in Paris, Venus was visible in the daytime sky, which led the inhabitants of the city and the surrounding area into amazement and fear. In 1799, General Bonaparte, returning from the conquest of Italy, also saw a wondrous heavenly diamond above his head. Perhaps then he believed in "his star."

Camille Flammarion's "Popular Astronomy" says that in ancient times, Aeneas, returning from Troy, saw Venus shining at its zenith during the day.

And here is what another French astronomer, Francois Arago, wrote in the book “Public Astronomy”: “... In 1716, the London mob considered the appearance Venus day for something wonderful. This gave Halley a reason to calculate the positions in which the planet appears in its largest volume ... "

Visibility conditions for Venus

But really, what are the conditions for the visibility of Venus? Particularly during the day? The best visibility - evening or morning - when Venus is in. For Venus, the maximum value is 48° (in rare cases, 52°). However, not at every elongation Venus is visible in the sky well enough. The best evening visibility is in February, March, April. Morning visibility during western elongation is best in autumn: in August, September, October. It is at this time of the year that it happens to be observed during the day.

“... Then a sign appeared in heaven, the star is bright, standing above the church, shining all day ...” - we read, for example, in the Pskov Chronicle. It was Venus on August 25, 1331. On that date, she was in western elongation, that is, she was a morning star, and her brightness was approaching the maximum possible.

Venus is at its brightest approximately 36 days before and 36 days after inferior conjunction. At maximum brightness, the apparent stellar magnitude of Venus reaches minus 4.6m and more.

It happens that from the bright Venus, objects on Earth give a shadow.

Of the nine planets in the solar system, Venus largest albedo(reflectivity) - 0.77, which is probably due to the carbon dioxide atmosphere of the planet. But Venus also receives about twice as much sunlight as the Earth. That is why, even on Mars, Venus is the brightest light in the sky after the Sun and the Martian moons.

Now a few words about the phases of Venus. It is known that people with exceptionally sharp eyesight can see the phases of Venus even with the naked eye. Like, for example, the mother of the famous mathematician Gauss. He invited his mother to look at Venus through an astronomical tube, he thought to amaze with an unprecedented sight: Venus in the form of a sickle. However, he himself had to be amazed.

The woman only asked why it is just with her eye that she sees a sickle turned in one direction, and through a telescope in the other ...

The moon is known to be at its brightest during the full moon phase. But the maximum brightness of Venus falls on the period when about 30 percent of its surface is illuminated. This is about halfway between its greatest elongation and inferior conjunction.

The entire sequence, the entire cycle of its phases, Venus passes almost exactly 5 times in 8 years. In astronomical language, it sounds like this: 5 synodic revolutions of Venus are made in 8 years.

Indeed: the average synodic Venus period about 584 days. If 5 x 584 = 2920 days. And 8 periods of the Earth's revolution around the Sun - 8 x 365.25 = 2922 days. That is a difference of only 2 days! That is why every 8 years the conditions for the visibility of Venus are almost exactly the same. That is, every 8 years Venus appears almost exactly in the same phase, almost exactly in the same place in the sky.

The diameter of the planet in different phases is not the same: a narrow sickle is much larger in diameter than a full disk. The reason is that in different phases the planet is removed from us at different distances (from 108 to 258 million kilometers). In the immediate vicinity of the Earth, Venus faces us with its unlit side, so we never see its largest phase. A full disk is visible only from the greatest distance. Venus is brightest for us when its angular diameter is 40″ and the angular width of the sickle is 10″. Then it shines 13 times brighter than Sirius - the brightest star in the earth's sky.

That is why on ancient steles, seals, amulets, Venus was painted with 8 rays. And the number 8 was considered sacred by many ancient peoples.

The Babylonians at the end of the III millennium BC. e. there was a calendar based on an 8-year cycle. "8 great deities of the primordial time" knew the Egyptians.

In Homer's Odyssey, the eighth year is repeatedly mentioned as a turning point, bringing decisive changes. In Greece, it was generally believed that significant events usually occurred in the eighth year. Orestes takes revenge for the murder of his father, committed 8 years ago.

According to one version of the myth of Theseus, the Athenians sent a terrible tribute to the monster Minotaur to Crete every 8 years.

The Thracians called the festival in honor of the god of light and arts Apollo the “eight years”. And in ancient Thebes, a holiday in honor of Apollo was celebrated every 8 years. The ancient Aztecs held a festival of "absorption of water and bread" every 8 years. The laws of Moses contain an indication: "And you will sow in the eighth year ..." The list could be continued. But even this is enough to understand the significance of Venus in the life of ancient peoples! Venus was by far the first of the "wandering stars" that man singled out because of its conspicuous brightness.

However, initially the ancient peoples took the “morning and evening stars” for two different ones. Morning Venus was called Phosphoros by the ancient Greeks, and Lucifer by the Latins, both words meaning "carrying light."

BUT evening Venus called - Vesper (Hesper), that is, "west", "evening".

The word Vesper in modern times means "evening prayer" in many languages.