Listed below are all five-letter points on the celestial sphere. A brief description is given for each definition.
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North
One of the four conventionally accepted cardinal directions, which is opposite to the south. On geographical map predominantly located at the top and indicated capital letter C (international designation N – north).
The magnetized compass needle always points north. The etymology of this word comes from the Old Russian language, translated as “cold”, “ cold wind" Also called the North (Far North) is the area that lies in this direction. The Far North and the North Pole are part of the territory of Russia.
It should be noted that, as geographical feature, The North Pole does not exist. This is a certain point that marks the axis of the Earth. The British James and John Ross were the first to talk about the existence of the North Pole. But the debate about who discovered it first is still going on. Due to the harsh climate (in winter – about – 40C, in summer – about 0C) animal world very scarce. Polar bears, walruses, and seals mainly live here. And because of eternal ice there is no vegetation at all.
West
One of four conditionally accepted by man cardinal directions. The point of west lies at the intersection of the celestial equator and the horizon, midway between north and south and opposite to east. On the geographical map, the west is indicated on the left with the letter Z (international designation is W “west”). The Word came to us from ancient times. The word west originally meant “sunset” because the Sun sets in the west (“sets” below the horizon), due to the rotation of the Earth around an imaginary axis from west to east. The area lying in this direction is also called the West.
Zenith
The etymology of this word is very complex. The word zenith is considered an error word, i.e. When borrowing words from other languages, a mistake is made in the word. So when borrowing the word zenith from Arabic, a typing error was made. The Arabic word "zamt", which meant "highest point in the sky", confused "m" with "in" to create the word "zanit", which later became "zenit". Zenith is some kind of imaginary celestial point, which is located above the observer's head.
Simply put, zenith is the direction that points “up” from a given point on earth, a direction that is strictly opposite to the direction of gravity at a given location. The angle between the horizon and the zenith is 90. The term zenith also refers to the highest point that is reached by a certain celestial body, as it moves through its orbit. So the word zenith is often used to determine the position of the Sun. There is an expression “The sun is at its zenith”, i.e. The sun has reached its highest point above the horizon at this location.
Nadir
This word is borrowed from Arabic. Nadir is an imaginary celestial point at which the celestial sphere and a vertical line directed downward from the observation point intersect. This point is located on the other half of the celestial sphere, invisible to humans due to the globe. Nadir is opposite to the zenith point, i.e. under the feet of the observer, on the other side of the Earth. The angle between nadir and horizon is 90?. Simply put, nadir is the direction opposite to the direction of zenith, which means the direction that coincides with the direction of gravity.
Apex
This term has Latin roots. The exact meaning of the word apex is "apex" from the Latin "apex". Apex is a certain point that is located in the celestial sphere; space objects are moving towards it at the moment. The opposite point is called the antiapex. Since all objects in the Universe are under the influence of gravitational forces and do not move in a straight line, their apexes are constantly shifting.
TEST . Celestial sphere (Gomulina N.N.)
1. The celestial sphere is:
A) an imaginary sphere of infinitely large radius, described around the center of the Galaxy;
B) a crystal sphere on which, according to the ancient Greeks, luminaries are attached;
C) an imaginary sphere of arbitrary radius, the center of which is the observer’s eye.
D) an imaginary sphere - the conditional border of our Galaxy.
2. Celestial sphere:
A) motionless, the Sun, Earth, other planets and their satellites move on its inner surface;
B) rotates around an axis passing through the center of the Sun, the period of rotation of the celestial sphere is equal to the period of revolution of the Earth around the Sun, i.e. one year;
B) rotates around the earth's axis with a period equal to the period of the earth's rotation around its axis, i.e. one day;
D) rotates around the center of the Galaxy, the period of rotation of the celestial sphere is equal to the period of rotation of the Sun around the center of the Galaxy.
3. The reason for the daily rotation of the celestial sphere is:
A) Proper motion of stars;
B) Rotation of the Earth around its axis;
B) The movement of the Earth around the Sun;
D) The movement of the Sun around the center of the Galaxy.
4. Center of the celestial sphere:
A) coincides with the eye of the observer;
B) coincides with the center of the Solar system;
B) coincides with the center of the Earth;
D) coincides with the center of the Galaxy.
5. The North Pole of the world at present:
A) coincides with the North Star;
B) is located 1°.5 from a Ursa Minor;
C) is located near the brightest star in the entire sky - Sirius;
D) is located in the constellation Lyra near the star Vega.
6. The constellation Ursa Major makes a full revolution around the North Star in a time equal to
A) one night;
B) one day;
B) one month;
D) one year.
7. The axis of the world is:
A) a line passing through the zenith Z and nadir Z" and passing through the eye of the observer;
B) a line connecting the points south S and north N and passing through the observer’s eye;
B) a line connecting points east E and west W and passing through the observer's eye;
D) A line connecting the poles of the world P and P" and passing through the eye of the observer.
8. The poles of the world are the points:
A) points north N and south S.
B) points of east E and west W.
C) the points of intersection of the axis of the world with the celestial sphere P and P";
D) the north and south poles of the Earth.
9. The zenith point is called:
10. The nadir point is called:
A) the point of intersection of the celestial sphere with a plumb line located above the horizon;
B) the point of intersection of the celestial sphere with a plumb line, located below the horizon;
C) the point of intersection of the celestial sphere with the axis of the world, located in the northern hemisphere;
D) the point of intersection of the celestial sphere with the axis of the world, located in the southern hemisphere.
11. The celestial meridian is called:
A) a plane passing through the noon line NS;
B) a plane perpendicular to the world axis P and P";
B) a plane perpendicular to the plumb line passing through the zenith Z and nadir Z";
D) a plane passing through the north point N, the world poles P and P, the zenith Z, the south point S.
12. The noon line is called:
A) a line connecting points east E and west W;
B) a line connecting points south S and north N;
B) a line connecting the points of the celestial pole P and the celestial poles P";
D) a line connecting the points of zenith Z and nadir Z".
13. The visible paths of stars when moving across the sky are parallel
A) the celestial equator;
B) celestial meridian;
B) ecliptic;
D) horizon.
14. The upper climax is:
A) the position of the luminary in which the height above the horizon is minimal;
B) the passage of the luminary through the zenith point Z;
C) the passage of the luminary through the celestial meridian and reaching greatest height above the horizon;
D) the passage of a star at an altitude equal to the geographic latitude of the observation site.
15. In the equatorial coordinate system, the main plane and the main point are:
A) the plane of the celestial equator and the vernal equinox point g;
B) horizon plane and south point S;
B) meridian plane and south point S;
D) the plane of the ecliptic and the point of intersection of the ecliptic and the celestial equator.
16. Equatorial coordinates are:
A) declination and right ascension;
B) zenith distance and azimuth;
B) altitude and azimuth;
D) zenith distance and right ascension.
17. Angle between the axis of the world and earth's axis equal to: A) 66°.5; B) 0°; B) 90°; D) 23°.5.
18. The angle between the plane of the celestial equator and the axis of the world is equal to: A) 66°.5; B) 0°; B) 90°; D) 23°.5.
19. The angle of inclination of the earth’s axis to the plane of the earth’s orbit is: A) 66°.5; B) 0°; B) 90°; D) 23°.5.
20. In what place on Earth does the daily movement of stars occur parallel to the horizon plane?
A) at the equator;
B) at mid-latitudes of the Earth’s northern hemisphere;
B) at the poles;
D) at mid-latitudes of the Earth's southern hemisphere.
21. Where would you look for the North Star if you were at the equator?
A) at the zenith point;
B) on the horizon;
22. Where would you look for the North Star if you were at the north pole?
A) at the zenith point;
B) at a height of 45° above the horizon;
B) on the horizon;
D) at an altitude equal to the geographic latitude of the observation site.
23. A constellation is called:
A) a certain figure of stars into which the stars are conventionally united;
B) a section of sky with established boundaries;
C) the volume of a cone (with a complex surface) extending to infinity, the apex of which coincides with the observer’s eye;
D) lines connecting the stars.
24. If the stars in our Galaxy move in different directions, and the relative speed of the stars reaches hundreds of kilometers per second, then we should expect that the outlines of the constellations change noticeably:
A) within one year;
B) for a time equal to the average duration of human life;
B) for centuries;
D) for thousands of years.
25. There are a total of constellations in the sky: A) 150; B)88; B)380; D)118.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 |
| IN | IN | B | A | B | B | G | IN | A | B | G | B | A | IN | A | A | B | IN | A | IN | IN | A | B | G | B |
It seems to us that all the stars are located on a certain spherical surface of the sky and are equally distant from the observer. In fact, they are located at different distances from us, which are so vast that the eye cannot notice these differences. Therefore, the imaginary spherical surface began to be called the celestial sphere.
Celestial sphere- this is an imaginary sphere of arbitrary radius, the center of which, depending on the problem being solved, is combined with one or another point in space. The center of the celestial sphere can be selected at the point of observation (the eye of the observer), at the center of the Earth or the Sun, etc. The concept of the celestial sphere is used for angular measurements, to study the relative position and movement of space objects in the sky.
The visible positions of all the luminaries are projected onto the surface of the celestial sphere, and for the convenience of measurements, a number of points and lines are constructed on it. For example, some of the stars in the “bucket” of Ursa Major are located far from one another, but for an earthly observer they are projected onto the same part of the celestial sphere.
A straight line passing through the center of the celestial sphere and coinciding with the direction of the plumb line at the observation point is called sheer or vertical line. It intersects the celestial sphere at points zenith(the upper point of intersection of the plumb line with the celestial sphere) and nadir(point of the celestial sphere opposite to the zenith). The plane passing through the center of the celestial sphere and perpendicular to the plumb line is called plane of true or mathematical horizon.
Vertical circle, or vertical luminary, is a large circle of the celestial sphere, passing through the zenith, luminary and nadir.
axis mundi- a straight line passing through the center of the celestial sphere parallel to the axis of rotation of the Earth, intersecting the celestial sphere at two diametrically opposite points.
The point of intersection of the axis of the world with the celestial sphere, near which the North Star is located, is called North Pole of the World, the opposite point - South Pole of the world. The North Star is located at an angular distance of about 1° (more precisely 44′) from the North Pole.
A great circle passing through the center of the celestial sphere and perpendicular to the axis of the world is called celestial equator. It divides the celestial sphere into two parts: North hemisphere with its summit at the North Pole and South- with the top at the South Pole.
Declension circle luminaries - a large circle of the celestial sphere passing through the poles of the world and the luminary.
Daily parallel- a small circle of the celestial sphere, the plane of which is perpendicular to the axis of the world.
The great circle of the celestial sphere passing through the zenith, nadir and poles of the world is called celestial meridian. The celestial meridian intersects with the true horizon at two diametrically opposite points. The point of intersection of the true horizon and the celestial meridian closest to the North Pole is called north point. The point of intersection of the true horizon and the celestial meridian closest to the South Pole is called point south. The line connecting the points north and south is called noon line. It lies on the plane of the true horizon. Shadows from objects at noon fall in the direction of the noon line.
The true horizon also intersects with the celestial equator at two diametrically opposite points - point of the east And point west. For an observer standing at the center of the celestial sphere facing the north point, the east point will be located on the right and the west point on the left. Remembering this rule, it is easy to navigate the terrain.
Points and lines of the celestial sphere - how to find the almucantarate, where the celestial equator passes, which is the celestial meridian.
What is the Celestial Sphere
Celestial sphere- an abstract concept, an imaginary sphere of infinitely large radius, the center of which is the observer. In this case, the center of the celestial sphere is, as it were, at the level of the observer’s eyes (in other words, everything that you see above your head from horizon to horizon is this very sphere). However, for ease of perception, we can consider the center of the celestial sphere and the center of the Earth; there is no mistake in this. The positions of stars, planets, the Sun and the Moon are plotted on the sphere in the position in which they are visible in the sky at a certain moment in time from a given point of location of the observer.
In other words, although observing the position of the stars on the celestial sphere, we, being in different places on the planet, will constantly see a slightly different picture, knowing the principles of the “working” of the celestial sphere, by looking at the night sky we can easily find our way around using simple technology. Knowing the view overhead at point A, we will compare it with the view of the sky at point B, and by the deviations of familiar landmarks, we will be able to understand where exactly we are now.
People have long come up with a number of tools to make our task easier. If you navigate the “terrestrial” globe simply using latitude and longitude, then a whole series of similar elements—points and lines—are also provided for the “celestial” globe—the celestial sphere.
The celestial sphere and the position of the observer. If the observer moves, then the entire sphere visible to him will move.
Elements of the celestial sphere
The celestial sphere has a number of characteristic points, lines and circles; let us consider the main elements of the celestial sphere.
Observer vertical
Observer vertical- a straight line passing through the center of the celestial sphere and coinciding with the direction of the plumb line at the observer’s point. Zenith- the point of intersection of the observer’s vertical with the celestial sphere, located above the observer’s head. Nadir- the point of intersection of the observer’s vertical with the celestial sphere, opposite to the zenith.
True horizon- a large circle on the celestial sphere, the plane of which is perpendicular to the observer’s vertical. The true horizon divides the celestial sphere into two parts: above-horizon hemisphere, at which the zenith is located, and subhorizontal hemisphere, in which the nadir is located.
Axis mundi ( Earth's axis) - a straight line around which the visible daily rotation of the celestial sphere occurs. The axis of the world is parallel to the axis of rotation of the Earth, and for an observer located at one of the poles of the Earth, it coincides with the axis of rotation of the Earth. The apparent daily rotation of the celestial sphere is a reflection of the actual daily rotation of the Earth around its axis. The celestial poles are the points of intersection of the axis of the world with the celestial sphere. The celestial pole, located in the region of the Ursa Minor constellation, is called North Pole world, and the opposite pole is called South Pole.
A great circle on the celestial sphere, the plane of which is perpendicular to the axis of the world. The plane of the celestial equator divides the celestial sphere into northern hemisphere, in which the North Pole is located, and southern hemisphere, where the South Pole is located.
Or the observer's meridian is a large circle on the celestial sphere, passing through the poles of the world, zenith and nadir. It coincides with the plane of the observer's earthly meridian and divides the celestial sphere into eastern And western hemisphere.
North and south points- the point of intersection of the celestial meridian with the true horizon. The point closest to the North Pole of the world is called the north point of the true horizon C, and the point closest to the South Pole of the world is called the south point S. The points of the east and west are the points of intersection of the celestial equator with the true horizon.
Noon Line- a straight line in the plane of the true horizon connecting the points of north and south. This line is called midday because at noon according to local true solar time, the shadow of a vertical pole coincides with this line, i.e., with the true meridian of a given point.
The intersection points of the celestial meridian with the celestial equator. The point closest to southern point horizon is called south point of the celestial equator, and the point closest to the northern point of the horizon is north point of the celestial equator.
Vertical of the luminary
Vertical of the luminary, or height circle, - a large circle on the celestial sphere, passing through the zenith, nadir and luminary. The first vertical is the vertical passing through the points of east and west.
Declension circle, or , is a large circle on the celestial sphere, passing through the poles of the world and the luminary.
A small circle on the celestial sphere drawn through a luminary parallel to the plane of the celestial equator. The apparent daily movement of the luminaries occurs along daily parallels.
Almucantarat luminaries
Almucantarat luminaries- a small circle on the celestial sphere drawn through the luminary parallel to the plane of the true horizon.
All the elements of the celestial sphere noted above are actively used to solve practical problems of orientation in space and determining the position of luminaries. Depending on the purpose and measurement conditions, two different systems are used spherical celestial coordinates.
In one system, the luminary is oriented relative to the true horizon and is called this system, and in the other, relative to the celestial equator and is called.
In each of these systems, the position of the star on the celestial sphere is determined by two angular quantities, just as the position of points on the surface of the Earth is determined using latitude and longitude.
The celestial sphere is an imaginary sphere of arbitrary radius, used in astronomy to describe the relative positions of luminaries in the sky. For simplicity of calculations, its radius is taken equal to one; The center of the celestial sphere, depending on the problem being solved, is combined with the observer’s pupil, with the center of the Earth, Moon, Sun, or even with an arbitrary point in space.
The idea of the celestial sphere arose in ancient times. It was based on the visual impression of the existence of a crystal dome of the sky, on which the stars seemed to be fixed. The celestial sphere in the minds of ancient peoples was the most important element of the Universe. With the development of astronomy, this view of the celestial sphere disappeared. However, the geometry of the celestial sphere, laid down in ancient times, as a result of development and improvement, received modern look, in which for the convenience of various calculations it is used in astrometry.
Let us consider the celestial sphere as it appears to the Observer at mid-latitudes from the surface of the Earth (Fig. 1).
Two straight lines, the position of which can be established experimentally using physical and astronomical instruments, play an important role in defining concepts related to the celestial sphere.
The first of them is a plumb line; This is a straight line that coincides at a given point with the direction of gravity. This line, drawn through the center of the celestial sphere, intersects it at two diametrically opposite points: the upper one is called the zenith, the lower one is called the nadir. The plane passing through the center of the celestial sphere perpendicular to the plumb line is called the plane of the mathematical (or true) horizon. The line of intersection of this plane with the celestial sphere is called the horizon.
The second straight line is the axis of the world - a straight line passing through the center of the celestial sphere parallel to the axis of rotation of the Earth; There is a visible daily rotation of the entire sky around the axis of the world.
The points of intersection of the axis of the world with the celestial sphere are called the North and South poles of the world. The most noticeable of the stars near the North Pole is the North Star. Bright stars There is no world near the South Pole.
The plane passing through the center of the celestial sphere perpendicular to the axis of the world is called the plane of the celestial equator. The line of intersection of this plane with the celestial sphere is called the celestial equator.
Let us recall that the circle that is obtained when the celestial sphere is intersected by a plane passing through its center is called a great circle in mathematics, and if the plane does not pass through the center, then a small circle is obtained. The horizon and celestial equator represent great circles of the celestial sphere and divide it into two equal hemispheres. The horizon divides the celestial sphere into visible and invisible hemispheres. The celestial equator divides it into the Northern and Southern Hemispheres, respectively.
During the daily rotation of the sky, the luminaries rotate around the axis of the world, describing small circles on the celestial sphere, called daily parallels; luminaries, 90° distant from the poles of the world, move along the great circle of the celestial sphere - the celestial equator.
Having defined the plumb line and the axis of the world, it is not difficult to define all other planes and circles of the celestial sphere.
The plane passing through the center of the celestial sphere, in which both the plumb line and the axis of the world lie simultaneously, is called the plane of the celestial meridian. The great circle from the intersection of this plane with the celestial sphere is called the celestial meridian. That of the points of intersection of the celestial meridian with the horizon, which is closer to the North Pole of the world, is called the north point; diametrically opposite - the point of the south. The straight line passing through these points is the noon line.
Points on the horizon that are 90° from the north and south points are called east and west points. These four points are called the main points of the horizon.
Planes passing through a plumb line intersect the celestial sphere in great circles and are called verticals. The celestial meridian is one of the verticals. The vertical perpendicular to the meridian and passing through the points of east and west is called the first vertical.
By definition, the three main planes - the mathematical horizon, the celestial meridian and the first vertical - are mutually perpendicular. The plane of the celestial equator is perpendicular only to the plane of the celestial meridian, forming a dihedral angle with the plane of the horizon. At the geographic poles of the Earth, the plane of the celestial equator coincides with the plane of the horizon, and at the equator of the Earth it becomes perpendicular to it. In the first case, at the geographic poles of the Earth, the axis of the world coincides with a plumb line and any of the verticals can be taken as the celestial meridian, depending on the conditions task at hand. In the second case, at the equator, the axis of the world lies in the plane of the horizon and coincides with the noon line; The North Pole of the world coincides with the point of north, and the South Pole of the world coincides with the point of south (see figure).
When using the celestial sphere, the center of which coincides with the center of the Earth or some other point in space, a number of features also arise, but the principle of introducing basic concepts - horizon, celestial meridian, first vertical, celestial equator, etc. - remains the same.
The main planes and circles of the celestial sphere are used when introducing horizontal, equatorial and ecliptic celestial coordinates, as well as when describing the features of the apparent daily rotation of luminaries.
The great circle formed when the celestial sphere is intersected by a plane passing through its center and parallel to the plane of the earth's orbit is called the ecliptic. The visible annual movement of the Sun occurs along the ecliptic. The point of intersection of the ecliptic with the celestial equator, at which the Sun passes from Southern Hemisphere celestial sphere in the North, is called the point of the vernal equinox. The opposite point of the celestial sphere is called the autumnal equinox. A straight line passing through the center of the celestial sphere perpendicular to the ecliptic plane intersects the sphere at two poles of the ecliptic: the North Pole in the Northern Hemisphere and the South Pole in the Southern Hemisphere.
