Why our nearest satellite moon is so important..
The moon being a satellite of the earth revolves around it. At the same time moon also rotates on its axis and the axis of the moon is more or less parallel to the axis of the earth (it is inclined at an angle about 580 43′. The moon has a diameter of about 3480 km and has the mass about 1/81 that of the earth. The following things we should know about the moon.
At the nearest point to the earth the moon is said to be in “perigee” , and the farthest in “apogee”. Like that of the earth, the moon’s orbit is also elliptical. The distance between earth and the moon varies from about 356000 km at perigee to about 407000 km at apogee.
SOME IMPORTANT FACTS:
- It takes 27 days 7hrs 43 min and 11.47 sec to complete one revolution around earth.
- It has gravitational pull 1/6 th of earth.
- We always see the same face of the satellite moon from the earth, not the complete surface of the earth.
- Only 59 percent of the total surface is visible from the earth. To our vision moon seems to be made up of bright and dark patches. The bright parts are the mountains and the highlands, while the darker patches are low lying plains.
- Moon has no atmosphere, no twilight and no sound. It takes 1.3 sec to reach the light on earth.
- Neil Armstrong and Buzz Aldrin reached moon on July 20, 1969 on Apollo XI and set the foot on 21 July, 1969. The landing spot is called “Sea of Tranquility”.
As the earth goes around the sun and the moon around the earth, the earth is also bound to come between the moon(satellite) and the sun once every lunar month. It causes an eclipse of the moon or the lunar eclipse. A lunar eclipse occurs on every full moon or new moon days. Again, for a lunar eclipse it is necessary that not only the sun, the moon and the earth in a straight line but they should also be located in same plane and this does not occur on every full moon days. A lunar eclipse can be of two types, “partial lunar eclipse” and “total lunar eclipse”.
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