The Moon is our space satellite.

The Moon Diameter 3474 km Mass 7,34*10^22 kg Density 3340 kg/m^3 The period of rotation 27,3 days The average distance from the Sun 0,00257 Þ.i. The period of revolution 27,3 years Excentricity of the orbit 0,055 The orbit’s slope 5,15°

The Moon is the natural satellite of the Earth and the nearest celestial body to it. The Moon plays a great role in astronomy as it can be achieved by both the autometic and the pilot spaceships. The first man on the moon was an American astronaut N. Armstrong.

The Moon surface.

In the Moon even naked eye can distinguish the dark parts (“seas”) and more light parts (“continents”). The Moon’s surface is covered with the great number of ring structures - ring mountain (circuses) and by shocked origin (meteoritic) (see the Moon craters and their peculiarity).

The Moon motion.

It is always turned to the Earth by one and the same semisphere (so called visible side of the Moon). We can see only 59% of the Moon’s surface due to the irregular motion of the Moon (see “the Moon libration”)

The period of the Moon turning around the Sun (a sinodic period) makes 29,53 days, so the Moon’s day or the Moon’s night durates 15 days each. The temperature in the Moon surface is changing from 400 to 100K.

The composition and structure of the Moon.

The density of the Moon’s solids is about 3,343 g/ sm3, that is less than the Earth’s one (5,518 g/ sm3). There is difference in the mineralogical composition of the Moon and of the Earth: for example, the oxides of iron in the Moon basalt are 25% - more, and titan - 13% more then in the terrestrial. The “sea” basalt in the Moon has more oxides of aluminium and calcium and relatively high density that connected them with the depth origin.

The depth of the Moon may be divided into five layers. The surface layer - the Moon’s bark (the thickness is from 60 km to 100 km). Its composition is just the nearest to the “continental’s” one. There is the upper cloak under the bark. The thickness is about 250 km. The middle cloak is deeper (500 km), there were the “sea” basalt’s formed. In 600 - 800 km deeper there lay the deep focused Moon seismic centres. But the natural Moon’s seismic activity is not very high in the Moon.

In the depth of 800 km the solid shell and, that is lithosphere and then being astenosphere - a molten layer, where only longitudinal waves are extended. The temperature of the upper part of astenosphere is about 1200 K.

The surface layer of the Moon is very crumbly, for it is broken by the solids: micrometeorites and the dust and big particles (see Regolit).

There is no gas atmosphere above the Moon due to its small mass.

The physical poles of the Moon.

The gravitational field of the Moon was thoroughly investigated. This is explained by the cosmonautics problems and gives the important information about the Moon. The acceleration of the gravity force on the Moon surface is 1,623 m/ c^2 i.e. 6 times less then on the Earth.

The magnetic field of the Moon is very weak and contains 0,1% of magnetic field of the Earth that corresponds to the intensity of the magnetic field not exceeding 0,5 gamma.

The Moon shines by the reflected light. The visual spherical albedo is 0,075 i.e. The Moon reflects only 7,5 of the solar light beams.

About the Moon origin.

It is interesting if the Earth and the Moon were the single unit, separated lately? The hypothesis about the Moon captured by the gravitational field of the earth is not convincing nowadays. According to the majority of the scientists theories, the Earth and the Moon were formed like as the different celestial bodies in the same sphere of the Solar system 4,3 - 4,6 bilious years ago.

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