The Moon

                            The  Moon

The Moon is the only natural satellite of the Earth. It takes the same 27.3 days to revolve round the Earth as well as to rotate on its axis. The Moon is a non-luminous body and it reflects the sunlight. The Moon mainly contains solid rock. It is dry and lifeless with no atmosphere or water. The surface is covered with dust, and large craters can be seen filled with solidified lava forming dark regions called maria or seas.

                       Origin of the Moon

Scientists put forth some theories about the origin of the Moon as follows:

The collision theory: This theory states that an external body in space hit the Earth, and a piece of solid material from Earth's mantle got separated and it orbited the Earth. This material gradually became the Moon.

The capture theory: This theory says that once the Moon was a planet revolving around the Sun. The gravity of the Earth caught it, and it became the satellite of the Earth.

The third moon formation theory: It states that the Earth and the Moon was formed at the same time in space as neighbouring bodies. These two bodies were formed from the gas and dust particles left behind after the formation of the Sun.

The escape theory: This theory says that once the Earth and the Moon were a single body. The gravity of the Sun formed a bulge on the Earth and later this bulge detached from the Earth to form the Moon.

                      Phases of the Moon

The Moon is a non-lummous body. Only the light of the Sun reflects on the Moon The shape of the Moon is seen changed while it revolves round the Earth This change occurs due to the changes in position with respect to the Earth and the Sun. When the position of the Moon comes in between the Earth and the Sun the side facing the Earth will be dark and it is called a New Moon. When the position of Earth comes in between the Sun and the Moon, the side of the Moon towards the Earth is seen fully illuminated and it is called a Full Moon. As the Moon travels from New Moon to Full Moon the illumination gradually increases and it is the Waxing of the Moon When it moves from Full Moon to New Moon the lighted portion gradually decreases and it is the Waning of the Maon. When the Moon seems larger than half of a Full Moon it is called Gibbous and when it seems amaller than half of a Full Moon it is called a Cresent. The Moon changes its shape step by step in about a month's time.

                              Eclipses

The Earth and the Moon are revolving constantly around the Sun by rotating on their own axis And so sometimes the Sun, the Earth and the Moon fall in a straight line. This is called an Eclipse When the Earth comes in between the Sun and the Moon, it blocks the rays of the Sun from reaching the Moon and the shadow of the Earth falls over the Moon. This is known as Lunar Eclipse. When the Moon comes in between the Sun and the Earth it blocks the Sun's rays from falling to the Earth. The Moon covers the Sun. The Sun and the sky seems to be dark for a few minutes. This is Solar Eclipse. It lasts only upto 7 minutes and 30 seconds.

                            The Moon

Distance from the earth in km.: 384403

Diameter in km.: 3476

Mass with respect to the earth: 0.012 (earth=1)

Gravity with respect to the earth: 0.167 Volume with respect to the earth: 0.02

Period of revolution: 27 days 7 hours 43 minutes

Period of rotation: 27 days 7 hours 43 minutes

Surface area: 38,000,000 sq.km.

Age: 460 crore years

Speed of revolution around the earth (km./hr.): 3700