The Moon SVG is a natural companion of the Earth. The closest satellite of the planet to the Sun, because the nearest planets to the Sun, Mercury and Venus, have no satellites. The second brightest object in the Earth’s sky is the Sun and the fifth largest natural satellite of the solar system. The average distance between the centers of the Earth and the Moon SVG is 384,467 km (0.002 57 a. u., ~ 30 diameters of the Earth).
The visible star value of the full Moon in the Earth’s sky is -12.71m. The illumination created by the full Moon near the Earth’s surface in clear weather is 0.25 – 1 lux.
The Moon is the only extraterrestrial astronomical object visited by man.
The Moon SVG as a celestial body
Since ancient times, people have tried to describe and explain the moon’s movement. Over time, more and more precise theories emerged.
The basis of modern calculations is Brown’s theory. Created at the turn of the XIX-XX centuries, it described the moon’s movement with the accuracy of measuring instruments of that time. Thus in calculation more than 1400 members (coefficients and arguments at trigonometric functions) were used.
Modern science can calculate the moon’s motion and check these calculations with even greater accuracy. Laser location methods measure the distance to the Moon with an error of a few centimeters. Not only do measurements have this accuracy, but also theoretical predictions of the Moon’s position; expressions with tens of thousands of terms are used for such calculations, and there is no limit to their number if even higher accuracy is required.
In the first approximation, we can assume that the Moon moves along an elliptical orbit with an eccentricity of 0.0549 and a large half-axis of 384,399 km. The actual motion of the Moon is quite complex and in its calculation it is necessary to take into account many factors, such as the flatness of the Earth and the strong influence of the Sun, which attracts the Moon in 2.2 times stronger than the Earth. More precisely, the moon’s movement around the Earth can be imagined as a combination of several motions:
The elliptical orbit of the Earth with a period of 27.32166 days is the so-called sideric month (i.e. the motion is measured relative to the stars);
The rotation of the lunar orbit plane: its nodes (points of intersection of orbit and ecliptic) move westward, making a full turn in 18.6 years. This movement is precessional;
a large axis of the lunar orbit (apsidal line) with a period of 8.8 years (in the opposite direction to the above-noted node movement, i.e. the longitude of the perigee increases);
periodic changes in the inclination of the lunar orbit with respect to the ecliptic from 4°59′ to 5°19′;
periodic changes in the size of the lunar orbit: perigee from 356.41 to 369.96 thousand km, apogee from 404.18 to 406.74 thousand km;
gradual removal of the Moon SVG from the Earth due to tidal acceleration (by 38 mm per year), thus, its orbit is a slowly spinning spiral.