Yakov Perelman entertaining astronomy. Book: Perelman Y. “Entertaining astronomy. The shortest path on Earth and on the map


	Ya. I. Perelman's book acquaints the reader with individual issues of astronomy, with its remarkable scientific achievements, tells in a fascinating way about the most important phenomena of the starry sky. The author shows many seemingly familiar and ordinary phenomena from a completely new and unexpected side and reveals their real meaning. sky .. Ya. I. Perelman died in 1942 during the blockade of Leningrad and did not have time to fulfill his intention to write a continuation of this book .. When working on the text, the publication was used: Perelman Ya. I. Entertaining astronomy. Edition 7th. Edited by P. G. Kulikovsky. - Moscow: State publishing house of technical and theoretical literature, 1954 .. 2nd edition, corrected ... Format: Soft glossy, 256 pages.
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Debut:	essay "Regarding the expected rain of fire"

Yakov Isidorovich Perelman(, -,) - Russian, scientist, popularizer, and, one of the founders of the genre, and founder, author of the concept sci-fi.

Biography

Yakov Isidorovich Perelman was born on December 4 (November 22, old style) 1882 in the city of Grodno province (now Bialystok is part of). His father worked as an accountant, his mother taught in elementary grades. The brother of Yakov Perelman, Osip Isidorovich, was a prose writer and wrote in Russian and in (pseudonym Osip Dymov).

1916 - the second part of the book "Entertaining Physics" was published.

Bibliography

Perelman's bibliography includes more than 1000 articles and notes published by him in various publications. And this is in addition to 47 popular science, 40 educational books, 18 school textbooks and teaching aids.

According to the All-Union Book Chamber, from year to year his books were published 449 times in our country alone; their total circulation was more than 13 million copies. They were printed:

in Russian 287 times (12.1 million copies);
in 21 languages of the peoples of the USSR - 126 times (935 thousand copies).

According to the calculations of the Moscow bibliophile Yu. P. Iroshnikov, the books of Ya. I. Perelman were published 126 times in 18 foreign countries in the following languages:

German - 15 times;
French - 5;
Polish - 7;
English - 18;
Bulgarian - 9;
Czech - 3;
Albanian - 2;
Hindi - 1;
Hungarian - 8;
modern Greek - 1;
Romanian - 6;
Spanish - 19;
Portuguese - 4;
Italian - 1;
Finnish - 4;
in oriental languages - 7;
other languages - 6 times.

Books

ABC of the metric system. L., Scientific publishing house, 1925
Quick account. L., 1941
To the world distances (about interplanetary flights). M., Publishing House of Osoaviakhim of the USSR, 1930
Fun tasks. Pg., Publishing House of A. S. Suvorin, 1914.
Evenings of entertaining science. Questions, tasks, experiments, observations from the field of astronomy, meteorology, physics, mathematics (co-authored with V. I. Pryanishnikov). L., Lenoblono, 1936.
Calculations with approximate numbers. M., APN USSR, 1950.
Newspaper sheet. electrical experiments. M. - L., Rainbow, 1925.
Geometry and the beginnings of trigonometry. A short textbook and a collection of tasks for self-education. L., Sevzappromburo of the Supreme Economic Council, 1926.
distant worlds. Astronomical essays. Pg., Publishing House of P. P. Soikin, 1914.
For young mathematicians. The first hundred puzzles. L., The Beginnings of Knowledge, 1925.
For young mathematicians. The second hundred puzzles. L., The Beginnings of Knowledge, 1925.
For young physicists. Experiences and entertainment. Pg., The Beginnings of Knowledge, 1924.
Live geometry. Theory and tasks. Kharkov - Kyiv, Unizdat, 1930.
Living Mathematics. Mathematical stories and puzzles. M.-L., PTI, 1934
Riddles in curiosities in the world of numbers. Pg., Science and school, 1923.
Entertaining Algebra. L., Time, 1933.
Entertaining arithmetic. Riddles and curiosities in the world of numbers. L., Time, 1926.
. L., Time, 1929.
Entertaining geometry. L., Time, 1925.
Entertaining geometry outdoors and at home. L., Time, 1925.
Entertaining mathematics. L., Time, 1927.
Entertaining mathematics in stories. L., Time, 1929.
Entertaining mechanics. L., Time, 1930.
Entertaining physics. Book. 1 St. Petersburg, Publishing House of P. P. Soikin, 1913.
Entertaining physics. Book. 2. Pg., Publishing House of P. P. Soikin, 1916 (until 1981 - 21 editions).
Entertaining tasks. L., Time, 1928.
Entertaining tasks and experiences. M., Detgiz, 1959.
Do you know physics? (Physical quiz for youth). M. - L., GIZ, 1934.
To the stars on a rocket. Kharkiv, Ukr. worker, 1934.
How to solve problems in physics. M. - L., ONTI, 1931.
Mathematics in the open air. L., Polytechnic School, 1931.
Mathematics at every turn. A book for extracurricular reading of FZS schools. M. - L., Uchpedgiz, 1931.
Between this and then. Experiences and entertainment for older children. M. - L., Rainbow, 1925.
Interplanetary travel. Flights to world space and reaching celestial bodies. Pg., Publishing House of P. P. Soikin, 1915 (10).
Metric system. Everyday handbook. Pg., Scientific publishing house, 1923.
Science at your leisure. L., Young Guard, 1935.
Scientific tasks and entertainment (puzzles, experiments, classes). M. - L., Young Guard, 1927.
Don't believe your eyes! L., Surf, 1925.
New and old measures. Metric measures in everyday life, their advantages. The simplest methods of translation into Russian. Pg., Ed. magazine "In the workshop of nature", 1920.
New problem book for a short course in geometry. M. - L., GIZ, 1922.
New Geometry Problem Book. Pg., GIZ, 1923.
Optical illusions. Pg., Scientific publishing house, 1924.
Flight to the moon. Modern projects of interplanetary flights. L., Sower, 1925.
Promotion of the metric system. Methodological guide for lecturers and teachers. L., Scientific publishing house, 1925.
Traveling on the planet (Physics of Planets). Pg., Publishing House of A. F. Marx, 1919.
Fun with matches. L., Surf, 1926.
Rocket to the moon. M. - L., GIZ, 1930.
Technical Physics. A manual for self-study and a collection of practical exercises. L., Sevzappromburo of the Supreme Economic Council, 1927.
Puzzle figures of 7 pieces. M. - L., Rainbow, 1927.
Physics at every turn. M., Young Guard, 1933.
Physical reader. A manual on physics and a book to read.
- Issue. I. Mechanics. Pg., Sower, 1922;
- issue II. Warmth, Pg., Sower, 1923;
- issue III. Sound. L., GIZ, 1925;
- issue IV. Light. L., GIZ, 1925.
Focuses and entertainment. The miracle of our age. Giant numbers. Between this and then. L., Rainbow, 1927.
Reader-problem book on elementary mathematics (for labor schools and self-education of adults). L., GIZ, 1924.
Tsiolkovsky. His life, inventions and scientific works. On the occasion of the 75th anniversary of the birth. M. - L., GTTI, 1932.
Tsiolkovsky K. E. His life and technical ideas. M. - L., ONTI, 1935.
Giant numbers. M. - L., Rainbow, 1925.
The miracle of our age. M. - L., Rainbow, 1925.
Young surveyor. L., Surf, 1926.
Box of riddles and tricks. M. - L., GPZ, 1929.

In the name of Perelman on the reverse side, 95 in diameter.

Notes

Links

Grigory Mishkevich, Doctor of Entertaining Sciences. M.: "Knowledge", 1986.
N. Karpushina, Yakov Perelman: touches to the portrait. , No. 5, 2007.

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Chapter One THE EARTH, ITS FORM AND MOVEMENTS
The shortest path on Earth and on the map
degrees of longitude and degrees of latitude
Where did Amundsen go?
Five kinds of counting time
Day length
Extraordinary shadows
The problem of two trains
Horizon countries by pocket watch
White nights and black days
Change of light and darkness
The Mystery of the Polar Sun
When the seasons begin
Three "ifs"
Another "if"
When are we closer to the Sun: at noon or in the evening?
One meter further
From different points of view
unearthly time
Where do months and years begin?
How many Fridays are in February?

CHAPTER TWO THE MOON AND ITS MOVEMENTS
Young or old month?
moon on flags
Riddles of the lunar phases
double planet
Why doesn't the moon fall on the sun?
The visible and invisible sides of the moon
The second moon and the moon of the moon
Why is there no atmosphere on the moon?
Dimensions of the lunar world
Lunar landscapes
moon sky
Why do astronomers observe eclipses?
Why do eclipses repeat after 18 years?
Is it possible to?
What Not Everyone Knows About Eclipses
What is the weather like on the moon?

CHAPTER THREE PLANETS
Planets in daylight
planetary alphabet
What can't be pictured
Why does Mercury have no atmosphere?
Phases of Venus
Great confrontations
Planet or lesser sun?
Disappearance of Saturn's rings
Astronomical anagrams
Planet Beyond Neptune
Dwarf planets
Our nearest neighbors
Companions of Jupiter
alien skies

CHAPTER FOUR STARS
Why do stars appear to be stars?
Why do stars twinkle and planets shine calmly?
Are the stars visible during the day?
What is a stellar magnitude?
Star Algebra
Eye and telescope
Star magnitude of the Sun and Moon
The true brilliance of the stars and the sun
The brightest star known
The star magnitude of the planets on the earth and alien sky
Why doesn't the telescope magnify the stars?
How are stars measured?
Giants of the starry world
An unexpected calculation
The heaviest substance
Why are stars called fixed?
Nearest star system
The scale of the universe

Chapter Five GRAVITY
From the gun up
Weight at high altitude
With a compass on planetary paths
The fall of the planets on the sun
Volcano's Anvil
The boundaries of the solar system
Error in Jules Verne's novel
How was the earth weighed?
What is the interior of the earth made of?
Weight of the Sun and Moon
Weight and density of planets and stars
Gravity on the Moon and planets
Record severity
Heaviness in the depths of the planets
The steamboat problem
Lunar and solar tides
moon and weather

ANNOTATION. Ya. I. Perelman's book acquaints the reader with individual issues of astronomy, with its remarkable scientific achievements, tells in a fascinating way about the most important phenomena of the starry sky. The author shows many seemingly familiar and ordinary phenomena from a completely new and unexpected side and reveals their real meaning.
The objectives of the book are to unfold before the reader a broad picture of the world space and the amazing phenomena occurring in it and to arouse interest in one of the most fascinating sciences, the science of the starry sky.
Ya. I. Perelman died in 1942 during the blockade of Leningrad and did not have time to fulfill his intention to write a continuation of this book.

FOREWORD

Astronomy is a happy science: it, in the words of the French scientist Arago, does not need decorations. Her achievements are so exciting that one does not have to make special efforts to draw attention to them. However, the science of the sky consists not only of amazing revelations and bold theories. It is based on everyday facts, repeated from day to day. People who do not belong to the number of sky lovers, in most cases, are rather vaguely familiar with this prosaic side of astronomy and show little interest in it, since it is difficult to focus attention on what is always in front of the eyes.
The everyday part of the science of the sky, its first, and not the last pages, constitute mainly (but not exclusively) the content of Entertaining Astronomy. It seeks above all to help the reader in understanding the basic astronomical facts. This does not mean that the book is something like an elementary textbook. The method of processing the material significantly distinguishes it from the educational book. Semi-familiar everyday facts are dressed here in an unusual, often paradoxical form, shown from a new, unexpected side, in order to sharpen attention to them and refresh interest. The exposition is, as far as possible, freed from special terms and from that technical apparatus, which often becomes an obstacle between an astronomical book and the reader.
Popular books are often reproached for the fact that nothing can be seriously learned from them. The reproach is justified to a certain extent and is supported (if we mean writings in the field of exact natural science) by the custom of avoiding any numerical calculations in popular books. Meanwhile, the reader really masters the material of the book only when he learns, at least in an elementary volume, to operate with it numerically. Therefore, in "Entertaining Astronomy", as in his other books of the same series, the compiler does not avoid the simplest calculations and only cares that they are offered in a dissected form and are quite drinkable for those familiar with school mathematics. Such exercises not only strengthen the acquired information more firmly, but also prepare for reading more serious works.
The proposed collection includes chapters relating to the Earth, the Moon, planets, stars, and gravitation, and the compiler chose mainly such material that is usually not considered in popular writings. The topics not presented in this collection, the author hopes to process over time in the second "book" of "Entertaining Astronomy". However, an essay of this type does not at all set itself the task of evenly exhausting all the richest content of modern astronomy.
I.P.

After the release in 1966 of the next edition of the book by Ya.I. Perelman "Entertaining Astronomy" more than forty years have passed. During this time, a lot has changed. People's knowledge of outer space has expanded to the same extent that objects of near and far space have become accessible to science. New opportunities for observational astronomy, the development of astrophysics and cosmology, the successes of manned cosmonautics, information from more and more advanced automatic interplanetary stations, the launching of powerful telescopes into near-Earth orbit, the "probing" of universal spaces with radio waves - all this constantly enriches astronomical knowledge. Of course, new astronomical information was also included in the forthcoming edition of Ya.I. Perelman.

In particular, the book was supplemented with new results of lunar exploration and updated data on the planet Mercury. The dates of the nearest solar and lunar eclipses, as well as oppositions of Mars, have been brought into line with modern knowledge.

Very impressive new information obtained with the help of telescopes and automatic interplanetary stations about the giant planets Jupiter, Saturn, Uranus and Neptune - in particular, about the number of their satellites and about the presence of planetary rings not only near Saturn. This information has also been included in the text of the new edition, where the structure of the book allows. New data on the planets of the solar system are included in the table "Planetary system in numbers".

The new edition also takes into account the changes in geographical and political-administrative names that appeared as a result of a change in power and the economic system in the country. The changes also affected the sphere of science and education: for example, astronomy is gradually withdrawn from the number of subjects studied in secondary schools, removed from compulsory school curricula. And the fact that the ACT publishing group continues to publish popular books on astronomy, including a new edition of the book by the great popularizer of science Ya.I. Perelman, gives hope that young people of new generations will still know something about their native planet Earth, the solar system, our galaxy and other objects of the universe.

N.Ya. Dorozhkin

EDITOR'S FOREWORD TO THE 1966 EDITION

Preparing for printing the 10th edition of "Entertaining Astronomy" Ya.I. Perelman, the editor and publisher believed that this was the last edition of this book. The rapid development of the science of the sky and the successes in the exploration of outer space have aroused the interest in astronomy among numerous new readers, who are entitled to expect to receive a new book of this plan, reflecting the events, ideas and dreams of our time. However, numerous persistent requests for a reprint of "Entertaining Astronomy" showed that the book by Ya.I. Perelman - an outstanding master of the popularization of science in an easy, accessible, entertaining, but at the same time quite strict form - has become in a certain sense a classic. And the classics, as you know, are reprinted countless times, introducing them to new and new generations of readers.

Preparing the new edition, we did not seek to bring its content closer to our "space age". We hope that there will be new books dedicated to the new stage in the development of science, which the grateful reader expects. We have made only the most necessary changes to the text. Basically, these are updated data on celestial bodies, indications of new discoveries and achievements, references to books published in recent years. As a book that can significantly expand the horizons of readers interested in the science of the sky, we can recommend "Essays on the Universe" by B.A. Vorontsov-Velyaminov, which, perhaps, have also become classics and have already gone through five editions. The reader will find many new and interesting things in the popular science journal of the USSR Academy of Sciences "Earth and Universe", devoted to the problems of astronomy, geophysics and space exploration. This journal began to appear in 1965 in the Nauka publishing house.

P. Kulikovsky

The everyday part of the science of the sky, its first, and not the last pages, constitute mainly (but not exclusively) the content of Entertaining Astronomy. It seeks above all to help the reader in understanding the basic astronomical facts. This does not mean that the book is something like an elementary textbook. The method of processing the material significantly distinguishes it from an educational book. Semi-familiar everyday facts are dressed here in an unusual, often paradoxical form, shown from a new, unexpected side, in order to sharpen attention to them and refresh interest. The exposition is, as far as possible, freed from special terms and from that technical apparatus, which often becomes an obstacle between an astronomical book and the reader.

Popular books are often reproached for not being able to seriously learn anything from them. The reproach is to a certain extent justified and is supported (if we have in mind writings in the field of exact natural science) by the custom of avoiding any numerical calculations in popular books. Meanwhile, the reader really masters the material of the book only when he learns, at least in an elementary volume, to operate with it numerically. Therefore, in "Entertaining Astronomy", as in his other books of the same series, the compiler does not avoid the simplest calculations and only cares that they are offered in a dissected form and are quite feasible for those familiar with school mathematics. Such exercises not only strengthen the acquired information more firmly, but also prepare for reading more serious works.

The proposed collection includes chapters relating to the Earth, the Moon, planets, stars, and gravitation, and the compiler chose mainly such material that is usually not considered in popular writings. Topics not presented in this collection, the author hopes to process over time in the second book of Entertaining Astronomy. However, a work of this type does not at all set itself the task of evenly exhausting all the richest content of modern astronomy.

Chapter first

THE EARTH, ITS FORM AND MOVEMENTS

The shortest path on Earth and on the map

Having outlined two points on the blackboard with chalk, the teacher offers the young student a task: to draw the shortest path between both points.

The student, after thinking, diligently draws a winding line between them.

- That's the shortest way! the teacher is surprised. - Who taught you that?

- My father. He is a taxi driver.

The drawing of a naive schoolboy is, of course, anecdotal, but wouldn't you smile if you were told that the dotted arc in fig. 1 is the shortest way from the Cape of Good Hope to the southern tip of Australia!

Even more striking is the following statement: depicted in Fig. 2 round trip from Japan to the Panama Canal is shorter than the straight line drawn between them on the same map!

Rice. 1. On a nautical chart, the shortest route from the Cape of Good Hope to the southern tip of Australia is not indicated by a straight line (“loxodrome”), but by a curve (“orthodromy”)

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Yakov Isidorovich Perelman
ENTERTAINING ASTRONOMY

EDITOR'S FOREWORD

N.Ya. Dorozhkin

EDITOR'S FOREWORD TO THE 1966 EDITION

P. Kulikovsky

AUTHOR'S FOREWORD

Chapter first
THE EARTH, ITS FORM AND MOVEMENTS

The shortest path on Earth and on the map

Having outlined two points on the blackboard with chalk, the teacher offers the young student a task: to draw the shortest path between both points.

The student, after thinking, diligently draws a winding line between them.

- That's the shortest way! the teacher is surprised. - Who taught you that?

- My father. He is a taxi driver.

Even more striking is the following statement: depicted in Fig. 2 round trip from Japan to the Panama Canal is shorter than the straight line drawn between them on the same map!

Rice. 1. On a nautical chart, the shortest route from the Cape of Good Hope to the southern tip of Australia is not indicated by a straight line (“loxodrome”), but by a curve (“orthodromy”)

All this looks like a joke, but meanwhile before you are indisputable truths, well known to cartographers.

Rice. 2. It seems incredible that the curved path connecting Yokohama on the sea chart with the Panama Canal is shorter than a straight line drawn between the same points

To clarify the issue, a few words will have to be said about charts in general and about nautical charts in particular. Depicting parts of the earth's surface on paper is not an easy task, even in principle, because the Earth is a sphere, and it is known that no part of the spherical surface can be deployed on a plane without folds and breaks. Involuntarily, one has to put up with the inevitable distortions on the maps. Many ways of drawing maps have been invented, but all maps are not free from shortcomings: some have distortions of one kind, others of a different kind, but there are no maps without distortions at all.

Sailors use maps drawn according to the method of an old Dutch cartographer and mathematician of the 16th century. Mercator. This method is called the Mercator projection. It is easy to recognize a sea chart by its rectangular grid: the meridians are shown on it as a series of parallel straight lines; circles of latitude - also in straight lines perpendicular to the first (see Fig. 5).

Imagine now that you want to find the shortest path from one ocean port to another on the same parallel. On the ocean, all paths are available, and it is always possible to travel there along the shortest path if you know how it lies. In our case, it is natural to think that the shortest path goes along the parallel on which both ports lie: after all, on the map it is a straight line, and what can be shorter than a straight path! But we are mistaken: the path along the parallel is not at all the shortest.

Indeed: on the surface of a sphere, the shortest distance between two points is the arc of the great circle connecting them. 1
big circle Any circle on the surface of a sphere whose center coincides with the center of this sphere is called. All other circles on the ball are called small.

But the circle of parallel small a circle. The arc of a large circle is less curved than the arc of any small circle drawn through the same two points: a larger radius corresponds to a smaller curvature. Pull the thread on the globe between our two points (cf. Fig. 3); you will make sure that it does not lie along the parallel at all. A stretched thread is an indisputable indicator of the shortest path, and if it does not coincide with a parallel on a globe, then on a sea chart the shortest path is not indicated by a straight line: remember that circles of parallels are depicted on such a map by straight lines, any line that does not coincide with a straight line , there is curve .

Rice. 3. A simple way to find the really shortest path between two points: you need to pull a thread on the globe between these points

After what has been said, it becomes clear why the shortest path on the sea chart is depicted not as a straight line, but as a curved line.

They say that when choosing the direction for the Nikolaev (now Oktyabrskaya) railway, there were endless disputes about which way to lay it. The disputes were put to an end by the intervention of Tsar Nicholas I, who solved the problem literally “straightforward”: he connected St. Petersburg with Moscow along the line. If this had been done on a Mercator map, it would have been an embarrassing surprise: instead of a straight line, the road would have turned out to be a curve.

Anyone who does not avoid calculations can be convinced by a simple calculation that the path that seems to us curved on the map is actually shorter than the one that we are ready to consider straight. Let our two harbors lie on the 60th parallel and be separated by a distance of 60°. (Whether such two harbors actually exist is, of course, immaterial for calculation.)

Rice. 4. To the calculation of the distances between points A and B on the ball along the arc of the parallel and along the arc of the great circle

On fig. 4 point O - center of the globe, AB - the arc of the circle of latitude on which harbors lie A and B; in her 60°. The center of the circle of latitude is at a point FROM Imagine that from the center O of the globe is drawn through the same harbors a great circle arc: its radius OB = OA = R; it will pass close to the drawn arc AB, but it doesn't match.

Let's calculate the length of each arc. Since the points BUT and AT lie at a latitude of 60°, then the radii OA and OV make up with OS(the axis of the globe) an angle of 30°. In a right triangle ASO leg AC (=r), lying opposite an angle of 30° is equal to half the hypotenuse JSC;

means, r=R/2 Arc length AB is one-sixth the length of the circle of latitude, and since this circle has half the length of the large circle (corresponding to half the radius), then the length of the arc of the small circle

To determine now the length of the arc of a great circle drawn between the same points (i.e., the shortest path between them), we need to know the magnitude of the angle AOW. Chord AS, subtracting the arc to 60 ° (small circle), is the side of a regular hexagon inscribed in the same small circle; that's why AB \u003d r \u003d R / 2

Drawing a straight line od, connecting center O the globe with the middle D chords AB, get a right triangle ODA, where is the angle D- straight:

DA=½AB and OA=R.

sinAOD=AD: AO=R/4:R=0.25

From here we find (according to the tables):

ﮮAOD=14°28′,5

and hence

ﮮAOB= 28°57′.

Now it is not difficult to find the desired length of the shortest path in kilometers. The calculation can be simplified if we recall that the length of a minute of a great circle of the globe is a nautical mile, i.e., about 1.85 km. Therefore, 28°57′ = 1737" ≈ 3213 km.

We learn that the path along the circle of latitude, shown on the sea chart by a straight line, is 3333 km, and the path along the large circle - along the curve on the map - 3213 km, i.e. 120 km shorter.

Armed with a thread and a globe at hand, you can easily check the correctness of our drawings and make sure that the arcs of the great circles really lie as shown in the drawings. Shown in fig. 1 as if the "straight" sea route from Africa to Australia is 6020 miles, and the "curve" - 5450 miles, i.e. shorter by 570 miles, or 1050 km. The "direct" air route on the sea chart from London to Shanghai cuts through the Caspian Sea, while the really shortest route lies north of St. Petersburg. It is clear what role these issues play in saving time and fuel.

If in the era of sailing shipping time was not always valued - then "time" was not yet considered "money", then with the advent of steam ships, one has to pay for each extra ton of coal consumed. That is why in our days ships are navigating along the really shortest path, often using maps made not in the Mercator, but in the so-called "central" projection: on these maps, the arcs of great circles are depicted as straight lines.

Why, then, did former navigators use such deceptive maps and choose unfavorable paths? It is a mistake to think that in the old days they did not know about the now indicated feature of sea charts. The matter is explained, of course, not by this, but by the fact that charts drawn according to the Mercator method, along with inconveniences, have very valuable benefits for sailors. Such a map, firstly, depicts separate small parts of the earth's surface without distortion, preserving the corners of the contour. This is not contradicted by the fact that with distance from the equator, all contours are noticeably stretched. At high latitudes, the stretch is so significant that a sea chart inspires a person who is unfamiliar with its features with a completely false idea of the true size of the continents: Greenland seems to be the same size as Africa, Alaska is larger than Australia, although Greenland is 15 times smaller than Africa, and Alaska together with Greenland half the size of Australia. But a sailor who is well acquainted with these features of the chart cannot be misled by them. He puts up with them, especially since, within small areas, a sea chart gives an exact likeness of nature (Fig. 5).

On the other hand, the sea chart greatly facilitates the solution of the tasks of navigational practice. This is the only kind of charts on which the path of a ship on a constant course is depicted as a straight line. To follow a "constant course" means to keep invariably one direction, one definite "rhumb", in other words, to go in such a way as to cross all the meridians at an equal angle. But this path ("loxodrome") can be depicted as a straight line only on a map on which all meridians are straight lines parallel to each other. 2
In reality, the loxodrome is a spiral line winding around the globe in a helical fashion.

And since on the globe the circles of latitude intersect with the meridians at right angles, then on such a map the circles of latitude should be straight lines perpendicular to the lines of the meridians. In short, we arrive precisely at the coordinate grid that constitutes a characteristic feature of the sea chart.

Rice. 5. Nautical or Mercator map of the globe. On such maps, the dimensions of contours far from the equator are greatly exaggerated. Which, for example, is bigger: Greenland or Australia? (answer in text)

Sailors' predilection for Mercator maps is now understandable. Wanting to determine the course to be followed when going to the designated port, the navigator applies a ruler to the end points of the path and measures the angle it makes with the meridians. Keeping in the open sea all the time in this direction, the navigator will accurately bring the ship to the target. You see that the "loxodrome" is, although not the shortest and not the most economical, but in a certain respect a very convenient way for a sailor. To reach, for example, from the Cape of Good Hope to the southern tip of Australia (see Fig. 1), one must always keep the same course S 87 °,50 ′. Meanwhile, in order to bring the ship to the same final point in the shortest way (along the "orthodromy"), it is necessary, as can be seen from the figure, to continuously change the ship's course: start from the course S 42 °, 50 ′, and end with the course N 53 °, 50 ′ (in this case, the shortest path is not even feasible - it rests on the ice wall of Antarctica).

Both paths - along the "loxodrome" and along the "orthodromy" - coincide only when the path along the great circle is depicted on the sea chart as a straight line: when moving along the equator or along the meridian. In all other cases, these paths are different.

degrees of longitude and degrees of latitude

Readers no doubt have a fair idea of geographic longitude and latitude. But I'm sure not everyone will give the correct answer to the following question:

Are degrees of latitude always longer than degrees of longitude?

Most people believe that each parallel circle is smaller than the meridian circle. And since the degrees of longitude are measured along parallel circles, while the degrees of latitude are measured along meridians, it is concluded that the former cannot anywhere exceed the length of the latter. At the same time, they forget that the Earth is not a regular ball, but an ellipsoid, slightly swollen at the equator. On the Earth's ellipsoid, not only is the equator longer than the meridian circle, but the parallel circles closest to the equator are also longer than the meridian circles. The calculation shows that up to about 5 ° latitude, the degrees of parallel circles (i.e., longitude) are longer than the degrees of the meridian (i.e., latitude).

Where did Amundsen go?

To which side of the horizon did Amundsen head, returning from the north pole, and to which side, returning from the south?

Give the answer without looking into the diaries of the great traveler.

The North Pole is the northernmost point on the globe.

Wherever we went from there, we would always go south.

Returning from the north pole, Amundsen could only head south; there was no other direction. Here is an extract from the diary of his flight to the North Pole on the airship "Norway":

“Norway has circled around the North Pole. Then we continued on our way ... The course was taken south for the first time since the airship left Rome. Similarly, from the south pole, Amundsen could only go to north .

Kozma Prutkov has a comic story about a Turk who ended up in the "most eastern" country. “And in front of the east, and from the sides of the east. And the west? Do you think, perhaps, that it is still visible, like some kind of dot, barely moving in the distance? .. Not true! And behind the east. In short: everywhere and everywhere the endless east.

Such a country, surrounded on all sides by the east, cannot exist on the globe. But there is a place on Earth, surrounded everywhere by the south, as well as a point surrounded on all sides by the "endless" north. At the north pole one could build a house with all four walls facing south. And this, in fact, could be done by our glorious Soviet polar explorers who visited the North Pole.

Five kinds of counting time

We are so accustomed to using pocket and wall clocks that we are not even aware of the significance of their testimony. Among readers, I am convinced, only a few will be able to explain what they actually mean when they say:

- It's seven o'clock now.

Is it really just that the small hand of the clock shows the number seven? What does this number mean? It shows that 7/24 days have elapsed in the afternoon. But after what noon and above all 7/24 what days?

What is a day? Those days, about which the well-known saying “day and night - a day away” speaks, represent a period of time during which the globe has time to turn around its axis once in relation to the Sun. In practice, it is measured as follows: two successive passages of the Sun (or rather, its center) are observed through that line in the sky that connects the point above the observer’s head (“zenith”) with the south point on the horizon. This interval is not always the same: the Sun comes to the indicated line a little earlier, sometimes later. It is impossible to adjust the clock according to this "true noon", the most skillful master is not able to align the clock so that it runs strictly according to the Sun: for this it is too sloppy. “The sun shows time deceptively,” wrote Parisian watchmakers on their coat of arms a hundred years ago.

Our clocks are regulated not by the real Sun, but by some imaginary sun that does not shine, does not heat, but was invented only for the correct calculation of time. Imagine that in nature there is a celestial body that moves uniformly throughout the year, bypassing the Earth in exactly the same time as it goes around the Earth - of course, in an apparent way - our truly existing Sun. This imaginative luminary in astronomy is called the "middle sun." The moment of its passage through the line zenith - south is called "middle noon"; the interval between two mean noons is the "mean solar day," and the time thus calculated is called "mean solar time." Pocket and wall clocks keep exactly this mean solar time, while a sundial, in which the shadow of the rod serves as an arrow, shows the true solar time for a given place. After what has been said, the reader probably has such an idea that the inequality of true solar days is caused by the uneven rotation of the Earth around its axis. The Earth really rotates unevenly, but the inequality of the day is due to the unevenness of another movement of the Earth, namely, its movement in orbit around the Sun. We will now understand how this can affect the length of the day. On fig. 6 you see two consecutive positions of the globe. Consider the left position. The arrows at the bottom show in which direction the Earth rotates on its axis: counterclockwise when looking at the north pole. At the point A now noon: this point lies just opposite the Sun. Imagine now that the Earth has made one complete rotation around its axis; during this time, she managed to move in orbit to the right and took another place. Earth radius drawn at a point A, has the same direction as a day ago, but the point A turns out to be not directly in front of the sun. For the man standing at the point A, noon has not yet arrived: the Sun is to the left of the drawn line. The earth needs to rotate for a few more minutes, so that at the point A it's a new afternoon.

Rice. 6. Why are the solar days longer than the sidereal ones? (Details in the text)

What follows from here? That the interval between two true solar noons longer the time it takes for the earth to rotate around its axis. If the earth were moving uniformly around the sun circle , in the center of which the Sun would be, then the difference between the actual duration of the rotation around the axis and the apparent one that we establish according to the Sun would be the same from day to day. It is easy to determine if we take into account that these small additions should make up a whole day during the year (the Earth, moving in orbit, makes one extra revolution around its axis per year); This means that the actual duration of each revolution is equal to

Note, by the way, that the "real" duration of the day is nothing but the period of rotation of the Earth in relation to any star; that is why such days are called "starry".

So the starry day average shorter than the sun by 3 m. 56 s, round count - by 4 m. The difference does not remain constant, because: 1) the Earth goes around the Sun not in uniform motion in a circular orbit, but in an ellipse, in some parts of which (closer to the Sun ) it moves faster, slower in others (more distant), and 2) the Earth's axis of rotation is inclined to the plane of its orbit. Both of these reasons determine that the true and mean solar time on different days diverge from each other by a different number of minutes, reaching up to 16 on some days. Both times coincide only four times a year:

On the contrary, in the days

the difference between the true and average time reaches its greatest value - about a quarter of an hour. The curve in fig. 7 shows how large this discrepancy is for different days of the year.

Until 1919, citizens of the USSR lived according to local solar time. For each meridian of the globe, the average noon occurs at a different time (“local” noon), so each city lived on his local time; only the arrival and departure of trains were scheduled according to the time common for the whole country: according to Petrograd. Citizens distinguished between "city" and "station" time; the first - local mean solar time - was shown by the city clock, and the second - Petrograd mean solar time - was shown by the clock of the railway station. Currently, in Russia, all railway traffic is carried out according to Moscow time.

Rice. 7. This graph, called the “Equation of Time Graph,” shows how large the discrepancy between true and mean noon is on a given day (left scale). For example, on April 1, at true noon, a correct mechanical clock should show 12:50; in other words, the curve gives the average time at true noon (right hand scale)

Since 1919, our calculation of the time of the day has been based on non-local time, called "zone" time. The globe is divided by meridians into 24 identical "belts", and all points of one belt calculate the same time, exactly the mean solar time that corresponds to the time of the middle meridian of this belt. On the entire globe, therefore, only 24 different times "exist" at any moment, and not many times, as it was before the introduction of the zone time account.

To these three types of time calculation - 1) true solar, 2) local mean solar and 3) zonal - we must add the fourth, used only by astronomers. This is 4) “sidereal” time, calculated according to the sidereal days mentioned earlier, which, as we already know, are shorter than the average solar by about 4 minutes. On September 22, both accounts of time coincide, but with each following day sidereal time is ahead of the mean solar time by 4 minutes.

Finally, there is also a fifth type of time - 5) the so-called maternity leave time - the one according to which the entire population of Russia and most Western countries live during the summer season.

Daylight savings time is exactly one hour ahead of standard time. The purpose of this event is as follows: during the daylight hours - from spring to autumn - it is important to start and end the working day early in order to reduce electricity consumption for artificial lighting. This is achieved by officially moving the hour hand forward. Such a transfer in Western countries is done every spring (at one o'clock in the morning the arrow is moved to the number 2), and every autumn the clock is again moved back.

Decree time was first introduced in our country in 1917; 3
At the initiative of Ya.I. Perelman, who proposed this bill. (Ed. note)

For a certain period, the clock was moved two and even three hours ahead; after several years of interruption, it was reintroduced in the USSR in the spring of 1930 and differs from the belt one hour.

Day length

The exact length of the day for each place and any date of the year can be calculated from the tables of the astronomical yearbook. Our reader, however, will hardly need such precision for everyday purposes; if he is ready to be content with a comparatively rough approximation, then the attached drawing will serve him well (Fig. 8). Along its left edge is shown in hours duration day. The angular distance of the Sun from the celestial equator is plotted along the lower edge. This distance, measured in degrees, is called the "declination" of the Sun. Finally, the oblique lines correspond to different latitudes of observation sites.

To use the drawing, you need to know how large the angular distance (“declination”) of the Sun from the equator in one direction or another for different days of the year. The corresponding data is given on the plate on page 28.

Rice. 8. Drawing for graphical determination of the length of the day (Details in the text)

We will show with examples how to use this drawing.

1. Find the length of the day in mid-April at latitude 60°.

We find in the tablet the declination of the Sun in mid-April, i.e., its angular distance these days from the celestial equator: + 10 °. On the bottom edge of the drawing, we look for the number 10 ° and draw a straight line from it at a right angle to the bottom edge until it intersects with an oblique line corresponding to the 60th parallel. On the left edge, the intersection point corresponds to the number 14 ½, i.e. the desired length of the day is approximately 14 hours 30 m.

When compiling this drawing, the influence of the so-called "atmospheric refraction" was taken into account (see p. 49, fig. 15).

The declination of the Sun on November 10 is -17°. (Sun in southern hemispheres of the sky.) Proceeding as before, we find 14 ½ hours. But since this time the declination is negative, the resulting number does not mean the duration of the day, but of the night. The desired length of the day is 24–14 ½ = 9 ½ hours.

We can also calculate the moment of sunrise. Dividing 9 ½ in half, we get 4 h. 45 m. Knowing from fig. 7, that on November 10, the clock at true noon shows 11:43, we find out the moment of sunrise. 11:43 – 4:45 = 6:58 e. at 4:28 p.m. Thus, both drawings (figs. 7 and 8), if properly used, can replace the corresponding tables of the astronomical yearbook.

Rice. 9. Schedule of sunrise and sunset during the year for the 50th parallel

You can, using the method just described, draw up for the latitude of your place of permanent residence for the whole year a schedule of sunrise and sunset, as well as the length of the day. An example of such a graph for the 50th parallel can be seen in Fig. 9 (it is compiled according to local, not standard time). After examining it carefully, you will understand how to draw such graphs. And having drawn it once for the latitude where you live, you can, by glancing at your drawing, immediately tell at about an hour the Sun will rise or set on one or another day of the year.

Yakov Isidorovich Perelman

ENTERTAINING ASTRONOMY

EDITOR'S FOREWORD

N.Ya. Dorozhkin

EDITOR'S FOREWORD TO THE 1966 EDITION

P. Kulikovsky

Chapter first

THE EARTH, ITS FORM AND MOVEMENTS

The shortest path on Earth and on the map

Having outlined two points on the blackboard with chalk, the teacher offers the young student a task: to draw the shortest path between both points.

The student, after thinking, diligently draws a winding line between them.

- That's the shortest way! the teacher is surprised. - Who taught you that?

- My father. He is a taxi driver.

Even more striking is the following statement: depicted in Fig. 2 round trip from Japan to the Panama Canal is shorter than the straight line drawn between them on the same map!

Rice. 1. On a nautical chart, the shortest route from the Cape of Good Hope to the southern tip of Australia is not indicated by a straight line (“loxodrome”), but by a curve (“orthodromy”)

All this looks like a joke, but meanwhile before you are indisputable truths, well known to cartographers.

Rice. 2. It seems incredible that the curved path connecting Yokohama on the sea chart with the Panama Canal is shorter than a straight line drawn between the same points

Yakov Perelman entertaining astronomy. Book: Perelman Y. “Entertaining astronomy. The shortest path on Earth and on the map

Biography