Star charts, celestial coordinates and time (§)

I. Determine the equatorial coordinates of the following stars from the star map:

• 1. b Ursa Major,
• 2. g Orion,
• 3. in China.

Answer. 1) b =11 hours, d =+620;

• 2)b =5 h 20 m, d =+60;
• 3) b =0 h 40 m, d = - 190 301

II. Find on the star map and name objects that have coordinates:

• 1) b =15 h 12 m, d = -9 0;
• 2)b =3 h 40 m, d =+48 0;

Answer. 1) in Libra and 2) d Perseus.

III. Find on the star map the three brightest stars located no further than 10 0 from the ecliptic and having a right ascension from 10 a.m. to 5 p.m. Determine their equatorial coordinates.

Answer. b Leo (b =10h 5m, d =+120); b Virgo (b =13h 20m, d =-110); b Scorpio (b =16h 25m, d =-260).

IV. Using PKZN, determine the declination and altitude at the upper culmination of the star Arcturus. Calculate the height of this star using the formula

(taking d from the table in an astronomy textbook), compare the results obtained and indicate with what accuracy the required quantities are determined from the star chart.

Answer. With c =570 301 we find from the map d =+190, h =500. Using the formula we get: h =510,571 (with d =190,271).

Composition of the solar system (§)

I. Having learned from the school astronomical calendar the coordinates of the planets observed today (in at the moment time), plot their positions on a star map, indicate in which constellations these planets are visible.

• · Using a moving map, indicate in which constellations these planets are visible.
• · Using a moving star chart, determine which of these planets are observed today at 10 p.m. and in which part of the sky.
• · Determine the rising and setting times of these planets today, and calculate the duration of their visibility.
• · Having learned from the school astronomical calendar the coordinates of the planets observed in the middle of two adjacent months, plot their positions on the star map and, having determined the direction of movement among the stars using an overhead circle, indicate whether each of these planets is moving forward or backward.

(Note: Regardless of the date, the overlay circle must be positioned so that the planet's path is above the horizon. If the planet is moving from west to east, its motion is direct.)

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Objective of the lesson: introduce students to stellar coordinates, instill the skills of determining these coordinates on a model of the celestial sphere.

Equipment: video projector, model of the celestial sphere

Lesson progress

Teacher: Since time immemorial, people have distinguished in the starry sky separate groups bright stars, united them into constellations, giving them names that reflected the way of life and the peculiarities of their thinking. This is what ancient Chinese, Babylonian, and Egyptian astronomers did. Many of the constellation names we use today come from Ancient Greece, where they took shape over the centuries.

Table 1 Chronicle of names

At the Congress of the International Astronomical Union in 1922, the number of constellations was reduced to 88. At the same time, the current boundaries between them were established.

It deserves special mention. That the proximity of stars in constellations is apparent, is how an observer from Earth sees them. In fact, the stars lag behind each other at great distances, and for us their visibility is, as it were, projected onto celestial sphere- an imaginary transparent ball, in the center of which is the Earth (observer), on the surface of which all the luminaries are projected as the observer sees them at a certain moment in time from a certain point in space. Presentation. Slide 1

Moreover, the stars in the constellations are different; they differ in apparent size and light. The brightest stars in the constellations are designated by letters of the Greek alphabet in descending order (a, b, g, d, e, etc.) of brightness.

This tradition was introduced by Alessandro Piccolomini (1508–1578), and consolidated by Johann Bayer (1572–1625).

Then John Flamsteed (1646–1719) within each constellation designated the stars by serial number (for example, the star 61 Cygnus). Stars with variable brightness indicate in Latin letters: R, S, Z, RR, RZ,AA.

Now we will look at how the location of the luminaries in the sky is determined.

Let's imagine the sky in the form of a giant globe of arbitrary radius, in the center of which the observer is located.

However, the fact that some luminaries are located closer to us, while others are further away, is not caught by the eye. Therefore, let us assume that all stars are at the same distance from the observer - on the surface celestial sphere. Presentation. Slide 1

Since the stars change their position during the day, we can conclude about the daily rotation of the celestial sphere (this is explained by the rotation of the Earth around its axis). The celestial sphere rotates around a certain axis PP` from east to west. The axis of apparent rotation of the sphere is the axis of the world. It coincides with the earth's axis or is parallel to it. The axis of the world intersects the celestial sphere at points P – north celestial pole and P`- South Pole peace. Up close north pole The polar star (a Ursa Minor) is located in the world. Using a plumb line, we determine the vertical and depict it in the drawing. Presentation. Slide 1

This straight line ZZ` is called plumb line. Z – zenith, Z`- nadir. Through point O - the intersection of the plumb line and the axis of the world - we draw a straight line perpendicular to ZZ`. This is NS - noon line(N- north, S – south). Objects illuminated by the Sun at noon cast a shadow in the direction along this line.

Two mutually perpendicular planes intersect along the noon line. A plane perpendicular to a plumb line that intersects the celestial sphere in a great circle is true horizon. Presentation. Slide 1

The plane perpendicular to the true horizon passing through the points Z and Z` is called celestial meridian.

We have drawn all the necessary planes, now let's introduce another concept. Let us arbitrarily place a star on the surface of the celestial sphere M, draw through points Z and Z` and M big semicircle. This - height circle or vertical

The instantaneous position of the star relative to the horizon and the celestial meridian is determined by two coordinates: height(h) and azimuth(A). These coordinates are called horizontal.

The altitude of the luminary is the angular distance from the horizon, measured in degrees, minutes, arc seconds ranging from 0° to 90°. More height replaced by an equivalent coordinate – z – zenith distance.

The second coordinate in the horizontal system A is the angular distance of the vertical of the luminary from the point of south. Defined in degrees minutes and seconds from 0° to 360°.

Notice how the horizontal coordinates change. Light M during the day describes on celestial sphere daily parallel is a circle of the celestial sphere, the plane of which is perpendicular axis mundi.

<Отработка навыка определения горизонтальных координат на небесной сфере. Самостоятельная работа учащихся>

When a star moves along the daily parallel, the highest point of ascent is called upper climax. Moving under the horizon, the luminary will end up at a point, which will be a point lower climax. Presentation. Slide 1

If we consider the path of the star we have chosen, we can see that it is rising and setting, but there are non-setting and non-rising luminaries. (Here - relative to the true horizon.)

Let's consider the change in the appearance of the starry sky throughout the year. These changes are not as noticeable for most stars, but they do occur. There is a star whose position changes quite dramatically, this is the Sun.

If we draw a plane through the center of the celestial sphere and perpendicular to the axis of the world PP`, then this plane will intersect the celestial sphere in a great circle. This circle is called celestial equator. Presentation. Slide 2

This celestial equator intersects with the true horizon at two points: east (E) and west (W). All daily parallels are located parallel to the equator.

Now let's draw a circle through the poles of the world and the observed star. The result is a circle - a circle of declination. The angular distance of the luminary from the plane of the celestial equator, measured along the declination circle, is called the declination of the luminary (d). Declination is expressed in degrees, minutes and seconds. Since the celestial equator divides the celestial sphere into two hemispheres (northern and southern), the declination of stars in the northern hemisphere can vary from 0° to 90°, and in the southern hemisphere - from 0° to -90°.

The declination of the luminary is one of the so-called equatorial coordinates.

The second coordinate in this system is right ascension (a). It is similar to geographic longitude. Right ascension is counted from points spring equinox(g). The Sun appears at the vernal equinox on March 21st. Right ascension is measured along the celestial equator in the direction opposite to the daily rotation of the celestial sphere. Presentation. Slide 2. Right ascension is expressed in hours, minutes and seconds of time (from 0 to 24 hours) or in degrees, minutes and seconds of arc (from 0° to 360°). Since the position of stars relative to the equator does not change when the celestial sphere moves, equatorial coordinates are used to create maps, atlases and catalogs.

Since ancient times it was noticed that the Sun moves among the stars and describes full circle in one year. The ancient Greeks called this circle ecliptic, which has been preserved in astronomy to this day. Ecliptic inclined to the plane of the celestial equator at an angle of 23°27` and intersects with the celestial equator at two points: the vernal equinox (g) and the autumn equinox (W). The Sun travels the entire ecliptic in a year; it travels 1° per day.

The constellations through which the ecliptic passes are called zodiac. Every month the Sun moves from one constellation to another. It is virtually impossible to see the constellation in which the Sun is located at noon, since it obscures the light of the stars. Therefore, in practice, at midnight we observe the zodiacal constellation, which is the highest above the horizon, and from it we determine the constellation where the Sun is located at noon (Figure No. 14 of the Astronomy 11 textbook).

We should not forget that the annual movement of the Sun along the ecliptic is a reflection of the actual movement of the Earth around the Sun.

Let us consider the position of the Sun on a model of the celestial sphere and determine its coordinates relative to the celestial equator (repetition).

<Отработка навыка определения экваториальных координат на небесной сфере. Самостоятельная работа учащихся>

Homework.

1. Know the contents of paragraph 116 of the Physics-11 textbook
2. Know the contents of paragraphs 3, 4 of the textbook Astronomy -11
3. Prepare material on the topic “Zodiac constellations”

Literature.

1. E.P. Levitan Astronomy 11th grade – Enlightenment, 2004
2. G.Ya. Myakishev and others. Physics 11th grade - Enlightenment, 2010
3. Encyclopedia for children Astronomy - ROSMEN, 2000

How can I find my star?

In addition to the Star Map, there are many other options for finding stars. Especially for you, OSR has developed several unique applications for convenient and fun search for stars - these are mobile application OSR Star Finder and One Million Stars browser app.

In this article we will describe in detail how to use several applications to find a star by name with coordinates RA 13h03m33.35 -49°31’38.1” dec 4.83 mag Cen.

All about coordinates

• Abbreviation RA means “Right Ascension”; "dec" means "declination". These values ​​are similar to latitude and longitude, but refer to celestial coordinates.
• Mag means “stellar magnitude” (English magnitude) and characterizes the brightness of a star. Bright stars reaching magnitude 6.5 can be seen with the naked eye. With binoculars you can see stars up to 10 magnitude units. To see stars with larger magnitudes, you will need an amateur telescope.
• Cen, in this case, means “Centaurus” - this is one of the 88 constellations in the sky. Knowing which constellation your star is in will make it easier to find it.

OSR Star Finder App

The OSR Star Finder app makes it easy to find a star in the night sky. To do this, you just need to enter the OSR code and point the phone at the sky. If the star is not visible, then you are in the other hemisphere. In this case, the application will help you determine when the star will become visible, and will also show you where it is visible from at a given time.

Google Earth

To find a star using free application Google Earth, follow these steps:

1. In the top panel, point to the ‘Planet’ icon and select ‘Sky’ from the drop-down list
2. On the left in the search window, enter the coordinates of the star in the following format: 13:03:33.35 -49:31:38.1. This information is extracted from the coordinates RA 13h03m33.35 -49°31’38.1” dec 4.83 mag Cen

You can also find a star via Google Sky from your personal page

The star dome for an earthly observer is in continuous rotation. If, being in the Northern Hemisphere of the planet, on a moonless and cloudless night you look long enough at the northern part of the sky, it will become noticeable that the entire diamond scattering of stars revolves around one inconspicuous dim star (only ignoramuses say that the Polar Star is the brightest). Some of the luminaries disappear behind the horizon in the western part of the sky; others take their place.

The carousel lasts until the morning. But the next day, at the same time, each star is again in its place. The coordinates of the stars relative to each other change so slowly that to people they seem eternal and motionless. It is no coincidence that our ancestors imagined the sky as a solid dome, and the stars as holes in it.

Strange star - reference point

A long time ago, our ancestors noticed one strange star. Its peculiarity is its immobility on the heavenly slope. It seemed to hover at one point above the northern edge of the horizon. All other celestial bodies describe regular concentric circles around it.

In what images did this star appear in the imagination of ancient astronomers? For example, among the Arabs it was considered a golden stake driven into the firmament. Around this stake gallops a golden stallion (we call Ursa Major), tied to it with a golden lasso (the constellation Ursa Minor).

It is from these observations that the celestial coordinates originate. Quite naturally and logically, the fixed star, which we call Polaris, became the starting point for astronomers to determine the location of objects on the celestial sphere.

By the way, for us, the residents Northern Hemisphere, I was very lucky with the star compass. By chance, of those that are one in a million, our Polar Star is located exactly on the line of the planet’s rotation axis, thanks to which the exact position relative to the cardinal points can be easily determined anywhere in the hemisphere.

First star coordinates

The technical means for precise measurement angles and distances, but people have been trying to at least somehow systematize and sort the stars for a long time. And even though the instruments used by ancient astronomy did not allow us to determine the coordinates of stars in the digitized form that is familiar to us, this was more than compensated for by imagination.

Since ancient times, inhabitants of all parts of the world divided the stars into groups called constellations. Most often, constellations were given names based on external resemblance with certain objects. So the Slavs simply called the constellation Ursa Major a ladle.

But greatest distribution received the names of the constellations, given in honor of the characters of the ancient Greek epic. It is possible, albeit with some stretch, to say that the names of the constellations and stars in the sky are their first primitive coordinates.

Pearls of the sky

Astronomers also paid attention to the most beautiful bright stars. They also received names in honor of Hellenic gods and heroes. So the alpha and beta constellations of Gemini are named Castor and Pollux, respectively, after the names of the sons of Zeus, the Thunderer, born after his next love adventure.

The star Algol, alpha, deserves special attention. According to legend, this hero, having defeated the fiend of the gloomy Tartarus in a mortal battle - the gorgon Medusa, who turns all living things into stone with her gaze, took her head with him as a kind of weapon (the eyes of even a severed head continued to “work”) . So, the star Algol is the eye of this very one in the constellation, and this is not entirely accidental. Ancient Greek observers noticed periodic changes in the brightness of Algol (double star system, the components of which periodically overlap each other for an earthly observer).

Naturally, the “winking” star became the eye of the fairy-tale monster. Coordinates of the star Algol in the sky: right ascension - 3 hours 8 minutes, declination +40°.

Celestial calendar

But we should not forget that the Earth rotates not only around its axis. Every 6 months a planet appears on the other side of the Sun. The picture of the night sky naturally changes. This has long been used by stargazers for precise definition seasons. For example, in Ancient Rome The students were looking forward to Sirius appearing in the morning sky (his name among the Romans was Vacation), because on these days they were sent home to rest. As you can see, the stellar name of these student leaves has been preserved to this day.

In addition to school holidays, the position of objects in the sky determined the beginning and end of sea and river navigation, and gave rise to military campaigns and agricultural activities. The authors of the first detailed calendars in different parts It was astrologers, stargazers, and temple priests who came to light and learned to accurately determine the coordinates of the stars. On all continents, where the remains of ancient civilizations are located, entire stone complexes are found, built for and measurements.

Horizontal coordinate system

Shows the coordinates of stars and other objects on the celestial sphere in the “here and now” mode relative to the horizon. The first coordinate is the height of the object above the horizon. The angular value is measured in degrees. Maximum value +90° (zenith). The coordinates of luminaries located on the horizon line have a zero coordinate value. And finally, objects located at the nadir point or at the observer’s feet have a minimum height value of -90° - zenith is the opposite.

The second coordinate is azimuth - the angle between horizontal lines directed towards the object and to the north. This system is also called topocentric because the coordinates are tied to a specific point on the globe.

The system is not without its shortcomings. Both coordinates of each star in it change every second. Therefore, it is not very suitable for describing, say, the location of stars in constellations.

Stellar GLONASS and GPS

How is such a system used? If you move across the planet over sufficiently long distances, the star image will certainly change. This was noticed by ancient sailors. For an observer standing at the very North Pole, the North Star will be at the zenith, directly above his head. But a resident of the equator will only be able to see Polar lying on the horizon line. Moving along the parallels (from east to west), the traveler will notice that the points and times of sunrise and sunset of certain celestial objects will also change.

This is what navigators learned to use to determine their location in the oceans. By measuring the angle of elevation above the horizon of the North Star, the ship's navigator obtained the latitude value. Using an accurate chronometer, the sailors compared the local noon time with the reference (Greenwich) and obtained longitude. Both earthly coordinates, apparently, could not be obtained without calculating the coordinates of stars and other celestial bodies.

For all its complexity and approximateness, the described system for determining location in space has faithfully served travelers for more than two centuries.

Equatorial first stellar coordinate system

In it, celestial coordinates are tied both to the surface of the earth and to landmarks in the sky. The first coordinate is declination. The angle between the line directed towards the star and the plane of the equator (the plane perpendicular to the axis of the world - the line of direction to the North Star) is measured. Thus, for stationary objects in the sky, such as stars, this coordinate always remains the same.

The second coordinate in the system will be the angle between the direction to the star and the celestial meridian (the plane in which the axis of the world and the plumb line intersect). Thus, the second coordinate depends on the position of the observer on the planet, as well as the moment in time.

The use of this system is very specific. It is used when installing and debugging the mechanisms of telescopes mounted on rotating platforms. Such a device can “follow” objects rotating along with the celestial dome. This is done to increase exposure time when photographing areas of the sky.

Equatorial No. 2 stellar

How are the coordinates of stars determined on the celestial sphere? For this there is a second equatorial system. Its axes are motionless relative to distant space objects.

The first coordinate, like the first equatorial system, is the angle between the star and the plane of the celestial equator.

The second coordinate is called right ascension. This is the angle between two lines lying on the plane of the celestial equator and intersecting at the point of its intersection with the axis of the world. The first line is laid to the point of the vernal equinox, the second - to the point of projection of the luminary onto the celestial equator.

The angle of right ascension is plotted along the arc of the celestial equator in a clockwise direction. It can be measured both in degrees from 0° to 360°, and in the hours: minutes system. Every hour is equal to 15 degrees.

The diagram shows how to measure the right ascension of a star.

What other star coordinates are there?

To determine our place among other stars, none of the above systems is suitable. Scientists record the positions of the nearest luminaries in the ecliptic coordinate system. It differs from the second equatorial one in that the base plane is the ecliptic plane (the plane in which the earth’s orbit around the Sun lies).

And finally, to determine the location of even more distant objects, such as galaxies and nebulae, the galactic coordinate system is used. It is not difficult to guess that the plane of the galaxy is taken as a basis. Milky Way(this is the name of our native spiral galaxy).

Is everything so perfect?

Not really. The coordinates of the polar star, namely the declination, is 89 degrees 15 minutes. This means that it is almost a degree away from the pole. For navigation, if a lost person is looking for a way, this arrangement is ideal, but for planning the course of a ship that has to travel thousands of miles, an adjustment had to be made.

And the immobility of stars is an apparent phenomenon. A thousand years ago (quite a bit by cosmic standards) the constellations had completely different outlines.

So, for a long time, scientists could not determine why in the Cheops pyramid an inclined tunnel goes from the burial chamber to the surface of one of the faces. Astronomy came to the rescue. The coordinates of the most bright stars V different periods time were calculated thoroughly, and astronomers suggested that during the construction of the pyramid, exactly on the line where this tunnel “looks”, there was the star Sirius - a symbol of the god Osiris, a sign of eternal life.

Astronomy is the whole world, full of beautiful images. This amazing science helps to find answers to the most important questions of our existence: to learn about the structure of the Universe and its past, about solar system, about the way the Earth rotates, and much more. There is a special connection between astronomy and mathematics, because astronomical predictions are the result of rigorous calculations. In fact, many problems in astronomy became possible to solve thanks to the development of new branches of mathematics.

From this book the reader will learn about how the position of celestial bodies and the distance between them is measured, as well as astronomical phenomena, during which space objects occupy a special position in space.

If the well, like all normal wells, was directed towards the center of the Earth, its latitude and longitude did not change. The angles that determine Alice’s position in space remained unchanged, only her distance to the center of the Earth changed. So Alice didn't have to worry.

Option one: altitude and azimuth

The most understandable way to determine coordinates on the celestial sphere is to indicate the angle that determines the height of the star above the horizon, and the angle between the north-south straight line and the projection of the star onto the horizon line - azimuth (see the following figure).

HOW TO MEASURE ANGLES MANUALLY

A device called a theodolite is used to measure the altitude and azimuth of a star.

However, there is a very simple, although not very accurate, way to measure angles manually. If we extend our hand in front of us, the palm will indicate an interval of 20°, the fist - 10°, thumb- 2°, little finger -1°. This method can be used by both adults and children, since the size of a person’s palm increases in proportion to the length of his arm.

Option two, more convenient: declination and hour angle

Determining the position of a star using azimuth and altitude is not difficult, but this method has a serious drawback: the coordinates are tied to the point at which the observer is located, so the same star, when observed from Paris and Lisbon, will have different coordinates, since the horizon lines in these cities will be located differently. Consequently, astronomers will not be able to use this data to exchange information about their observations. Therefore, there is another way to determine the position of the stars. It uses coordinates reminiscent of the latitude and longitude of the earth's surface, which astronomers can use at any point globe. This intuitive method takes into account the position of the Earth's rotation axis and assumes that the celestial sphere rotates around us (for this reason, the Earth's rotation axis was called the axis mundi in Antiquity). In reality, of course, the opposite is true: although it seems to us that the sky is rotating, in fact it is the Earth that is rotating from west to east.

Let us consider a plane cutting the celestial sphere perpendicular to the axis of rotation passing through the center of the Earth and the celestial sphere. This plane will intersect earth's surface along the great circle - the earth's equator, and also the celestial sphere - along its great circle, which is called the celestial equator. The second analogy with earthly parallels and meridians would be the celestial meridian, passing through two poles and located in a plane perpendicular to the equator. Since all celestial meridians, like terrestrial ones, are equal, the prime meridian can be chosen arbitrarily. Let us choose as the zero meridian the celestial meridian passing through the point at which the Sun is located on the day of the vernal equinox. The position of any star and celestial body is determined by two angles: declination and right ascension, as shown in the following figure. Declination is the angle between the equator and the star, measured along the meridian of a place (from 0 to 90° or from 0 to -90°). Right ascension is the angle between the vernal equinox and the meridian of the star, measured along the celestial equator. Sometimes, instead of right ascension, the hour angle, or the angle that determines the position of the celestial body relative to the celestial meridian of the point at which the observer is located, is used.

The advantage of the second equatorial coordinate system (declination and right ascension) is obvious: these coordinates will be unchanged regardless of the position of the observer. In addition, they take into account the rotation of the Earth, which makes it possible to correct the distortions it introduces. As we have already said, the apparent rotation of the celestial sphere is caused by the rotation of the Earth. A similar effect occurs when we are sitting on a train and see another train moving next to us: if you do not look at the platform, you cannot determine which train has actually started moving. We need a starting point. But if instead of two trains we consider the Earth and the celestial sphere, finding an additional reference point will not be so easy.

In 1851 a Frenchman Jean Bernard Leon Foucault (1819–1868) conducted an experiment demonstrating the motion of our planet relative to the celestial sphere.

He suspended a load weighing 28 kilograms on a 67-meter-long wire under the dome of the Parisian Pantheon. The oscillations of the Foucault pendulum lasted 6 hours, the oscillation period was 16.5 seconds, the pendulum deflection was 11° per hour. In other words, over time, the plane of oscillation of the pendulum shifted relative to the building. It is known that pendulums always move in the same plane (to verify this, just hang a bunch of keys on a rope and watch its vibrations). Thus, the observed deviation could be caused by only one reason: the building itself, and therefore the entire Earth, rotated around the plane of oscillation of the pendulum. This experiment became the first objective evidence of the rotation of the Earth, and Foucault pendulums were installed in many cities.

The Earth, which appears to be motionless, rotates not only on its own axis, making a complete revolution in 24 hours (equivalent to a speed of about 1600 km/h, that is, 0.5 km/s if we are at the equator), but also around the Sun , making a full revolution in 365.2522 days (from average speed approximately 30 km/s, that is, 108,000 km/h). Moreover, the Sun rotates relative to the center of our galaxy, completing a full revolution every 200 million years and moving at a speed of 250 km/s (900,000 km/h). But that’s not all: our galaxy is moving away from the rest. Thus, the movement of the Earth is more like a dizzying carousel in an amusement park: we spin around ourselves, move through space and describe a spiral at breakneck speed. At the same time, it seems to us that we are standing still!

Although other coordinates are used in astronomy, the systems we have described are the most popular. It remains to answer last question: how to convert coordinates from one system to another? The interested reader will find a description of all the necessary transformations in the application.

MODEL OF THE FOUCAULT EXPERIMENT

We invite the reader to conduct a simple experiment. Let's take a round box and glue a sheet of thick cardboard or plywood onto it, onto which we will attach a small frame in the shape of a football goal, as shown in the figure. Let's place a doll in the corner of the sheet, which will play the role of an observer. We tie a thread to the horizontal bar of the frame, on which we attach the sinker.

Let's move the resulting pendulum to the side and release it. The pendulum will oscillate parallel to one of the walls of the room in which we are located. If we begin to smoothly rotate the sheet of plywood together with the round box, we will see that the frame and the doll will begin to move relative to the wall of the room, but the plane of oscillation of the pendulum will still be parallel to the wall.

If we imagine ourselves as a doll, we will see that the pendulum moves relative to the floor, but at the same time we will not be able to feel the movement of the box and the frame on which it is attached. Similarly, when we observe a pendulum in a museum, it seems to us that the plane of its oscillations is shifting, but in fact we ourselves are shifting along with the museum building and the entire Earth.

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