The celestial sphere has its main elements: points, lines, planes. Celestial sphere point Celestial sphere point 5 crossword clue

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 the southern point of the 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.

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 a geographical map it is predominantly located at the top and is designated by the 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 a geographical object, 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 (about -40C in winter, about 0C in summer), the fauna is very scarce. Polar bears, walruses, and seals mainly live here. And because of the eternal ice, there is no vegetation at all.

West

One of the four cardinal directions conventionally accepted by man. 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 mistake was made during rewriting. 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 an imaginary celestial point that 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 reached by a certain celestial body as it moves along 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.

§ 48. Celestial sphere. Basic points, lines and circles on the celestial sphere

Let us consider the main points and circles of the celestial sphere, the center of which is taken to be the eye of the observer (Fig. 72). Let's draw a plumb line through the center of the celestial sphere. The points of intersection of the plumb line with the sphere are called zenith Z and nadir n.

Rice. 72.

The straight line passing through the center of the celestial sphere parallel to the earth's axis is called the mundi axis. The points of intersection of the axis of the world with the celestial sphere are called poles of the world. One of the poles, corresponding to the poles of the Earth, is called the north celestial pole and is designated Pn, the other is the south celestial pole Ps.

The QQ plane passing through the center of the celestial sphere perpendicular to the axis of the world is called plane of the celestial equator. This plane, intersecting with the celestial sphere, forms a great circle - celestial equator, which divides the celestial sphere into northern and southern parts.

The great circle of the celestial sphere passing through the celestial poles, zenith and nadir, is called observer's meridian PN nPsZ. The mundi axis divides the observer's meridian into the midday PN ZPs and midnight PN nPs parts.

The observer's meridian intersects with the true horizon at two points: the north point N and the south point S. The straight line connecting the points of north and south is called midday line.

If you look from the center of the sphere to point N, then on the right there will be a point of east O st, and on the left - a point of west W. Small circles of the celestial sphere aa", parallel to the plane of the true horizon, are called almucantarates; small bb" parallel to the plane of the celestial equator, - heavenly parallels.

The circles of the celestial sphere Zon passing through the zenith and nadir points are called verticals. The vertical line passing through the points of east and west is called the first vertical.

The circles of the celestial sphere of PNoPs passing through the poles of the world are called declination circles.

The observer's meridian is both a vertical and a circle of declination. It divides the celestial sphere into two parts - eastern and western.

The celestial pole located above the horizon (below the horizon) is called the elevated (lowered) celestial pole. The name of the elevated celestial pole is always the same as the name of the latitude of the place.

The axis of the world makes an angle with the plane of the true horizon equal to geographical latitude of the place.

The position of luminaries on the celestial sphere is determined using spherical coordinate systems. In nautical astronomy, horizontal and equatorial coordinate systems are used.