4th Class Science Our Universe Satellites

Satellites

Category : 4th Class

Satellites

Satellites are free flying objects that move around a planet. There are mainly two types of satellites, natural and artificial. Natural satellites as the name suggest, are naturally present in the space. They are the heavenly bodies formed along with the planets and the stars of the galaxies. Artificial satellites or manmade satellites are those free flying objects that are orbiting the earth or planet and used for various purposes like communication, weather information etc. Most of the planets in our solar systems have their own natural satellites. The inner planets (planets close to the sun) have less number of natural satellites when compared to the outer planets. Earth, the 3rd planet from the sun has only one satellite. We better know it as moon. The red planet mars has two satellites. The outer four planets of our solar system is known for many satellites. Jupiter, the largest planet is said to have as many as sixty four (64) known moons. Jupiter's moons are of different types. Some of them are much bigger than earth's moon, where as some are tiny, only a few miles across. The ringed planet, Saturn is said to have sixty two (62) moons orbiting it. Titan is the largest moon of Saturn. Uranus is known till date to have twenty (20) moons. Neptune is the farthest planet having eight (8) known moons. The number may be more.

Moon

Moon, which looks the brightest and biggest on a dark night is the only natural satellite of the earth. There is no life on the moon because of extreme temperature. This extreme temperature is due to lack of atmosphere. On the moon, as there is no atmosphere it becomes boiling hot during the day and freezing cold at night. Moon does not have light of its own. The bright moon as we see, is due to the reflection of sun's light from its surface.

Moon of the earth

The surface of the moon is dusty and barren. There are many craters of different sizes on its surface. It also has large number of steep and high mountains. We can see mountains and craters on the moon from the earth with the help of a telescope. Most interesting fact about the moon is that its lighted or the bright part changes its shape every day. This is because, as we already known that, moon doesn't have any light of its own. It reflects the light of the sun. When the moon moves in its orbit around the earth, different portion of the moon's surface reflects light from the sun. It is only that part of the moon, which reflects sunlight is seen by us and the rest of the moon is dark. This increasing and decreasing size of the lighted part of the moon is known as phases of the moon.

Showing the Phase of the Moon

Moon is always been a object of wonder for us. It was on 21st July 1969 Neil Armstrong the first man who landed on moon, and the spacecraft was APOLLO 11

Neil Armstrong

Artificial Satellites

Artificial satellites or manmade satellites are placed in the space orbiting the earth and are used for various purposes like communication, weather prediction etc. In the search of knowledge and better life style, scientists have been successfully and continuously placing artificial satellite around the earth. These artificial satellites are sent by rockets. They revolve around the earth. Weather satellite takes pictures of the clouds and wind systems. This helps to forecast the weather. Some satellites are used to photograph the earth from above and give valuable information about our natural resources. Various scientific satellites are used to gather information’s about stars, planets, galaxies and our outer space. There are even spy satellites, which take picture for the military purposes. The world’s first artificial satellite was SPUTNIK 1 launched on 4th October 1957 by the Russians.

Sputnik 1

India has built and launched several artificial satellites. ARYABHATTA was the 1st Indian satellite. Other Indian satellites are INSAT, KALPANA-1, EDUSAT, 1RS etc.