Lunar surface coordinates, foreign name: Lunar surface coordinates, is used to mark the position of the earth's satellite and the moon's surface.Any position on the surface of the moon can be indicated by two sets of numbers corresponding to the longitude and latitude of the earth.Astronomers use a small bowl shaped crater (&# 39; Mostin A&# 39;) as the reference point to define the lunar surface coordinates.
Lunar coordinatesIt is used to markearthSatellite,MoonPosition on the surface.Any position on the surface of the moon can pass throughlongitudeandlatitudeThe two sets of numbers indicate the location.Longitude gives the longitude at the meridian of the moon (this is the longitude through the central point of the surface on the side of the moon facing the earth, seeEarth's prime meridian）To the east or west of, this point is considered to be the middle point of the lunar surface visible from the earth;Latitude gives the position south or north of the lunar equator.Both coordinate values are expressed in degrees.
Astronomers used a small bowl shaped crater ('Mostin A') as the datum point defining the coordinates of the lunar surface.The coordinates of this crater are defined as follows:
Latitude: 3 ° 12 ′ 43.2 ″ S
Longitude: 5 ° 12 ′ 39.6 ″ west longitude
This coordinate system has beenLunar laser ranging experimentPrecise definition.
The surface between longitude 90 ° E and 90 ° W can be seen from the earth, but becauseLibration So that the total surface on both sides of the moon that we can see reaches59%。
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The position of any place on our earth is determined by geographical longitude and latitude.The location of the moon surface can also be represented by similar longitude and latitude, which are called longitude (λ) and latitude (β) of the moon surface.But how to determine the origin of longitude and latitude of the lunar surface?In 1679 AD, French astronomer Cassini (1677-1756) discovered that the moon has a rotation (the rotation period is equal to the period of the moon's revolution around the earth), and the position of the rotation axis in the moon body is fixed.In this way, with rotation, the south, north pole and equator can be determined.Like the longitude and latitude network of the earth, we can draw the longitude and latitude network on the surface of the moon.The large circle along the north and south poles is called the longitude circle, and the small circle parallel to the equator is called the latitude circle[1]。
To determine the longitude of the moon, first select a longitude line as the initial longitude line (similar to the prime meridian on the earth).In 1749, German astronomer Mayer (1723~1762) suggested that when the moon was on the intersection line (the line between the two intersections of the white and the ecliptic) and the arch line (the line between the apogee and perigee of the moon) at the same time, the longitude line of the center of the moon viewed from the center of the earth should be regarded as the "initial longitude".It is also stipulated that the longitude from this line to the west of the moon wheel (the side with dangerous sea) is positive (or marked with letter E), and the longitude from this line to the east of the moon wheel (the side with storm ocean) is negative (or marked with letter W).Longitude ranges from 0 ° to ± 180 °.
The moon always faces us with a hemisphere, so the origin of the longitude and latitude network on the lunar surface should be near the center of the moon wheel.Just near the center is a small crater called MostingA.It's easy to find it in the picture of the full moon.To the naked eye, it is a bright little idea.It can be measured for a period of time from the top chord to the bottom chord.As long as the exact position of this point is measured, the coordinates of other places can be determined relative to it.
Mostin is located inFramarion CraterIt is 13.05 km in diameter to the west of.Since the end of the last century, many people have observed with a heliometer (goniometer).The German astronomical almanac (Berlin version) in 1960 adopted the observation results of F. Hayn et al., and the coordinates of point A in Mostin are:
λ0=- 5°10′07″
β0=- 3°11′02″
This value is adopted by astronomical almanacs of various countries.In 1967, Japanese astronomer Gu Zaiyou reorganized the past observation data, and obtained the longitude and latitude of the moon surface at the Mostin crater:
λ0=- 5°09′50″± 4″.5
β0=- 3°10′47″± 4″.4
With this coordinate, the longitude and latitude of other places on the lunar surface can be determined.
