The sun, eight planets, their moons and other heavenly bodies constitute bodies constitute our solar system.
Planets are heavenly bodies that revolve around the Sun. They do not have any light of their own. They reflect the light of the Sun.
The Solar System
The eight planets in the order of increasing distance from the Sun are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Pluto was considered as the ninth plant of the solar system until scientist reclassified it as a dwarf planet. On August 24, 2006 international Astronomical Union redefined planet. Pluto did not fit into this definition and is now considered as a dwarf planet.
Earth is the only planet where life exists because it has an atmosphere, water and right temperature.
Moon is a heavenly body that goes around the planet. It is also knows as a Satellite. The moon is about 3, 86, 000 km away from the earth. It is much smaller than the Earth and is a natural satellite of the Earth. It does not have any light of its own, but shines because it reflects the light of the Sun that falls on it.
Conditions on the Moon
The surface of the Moon is uneven. It has mountains and millions of big round pits called craters. These craters are formed due to the crashing of meteorites into the surface of the Moon.
The surface of the Moon is also covered with a thick layer of dust. But on the Moon there is no atmosphere. It becomes boiling hot during the day and freezing cold at night. As there is no air on the Moon, hence, no life can exist there.
Due to absence of air, no sound can be heard on the Moon. The sky is always black and there are no clouds to hide the Sun.
Landing on the Moon
The American space craft Appolo XI successfully landed on the Moon on July 21, 1969. Neil Armstrong and Edwin Aldrin stepped on the Moon’s surface.
What is Eclipse?
An eclipse is formed when the Sun light is blocked by some heavenly body. These are two types: Lunar Eclipse and Solar Eclipse
Lunar Eclipse is formed when the earth comes between the sun and the moon and the shadow of the earth falls on the moon.
If the moon’s surface is completely hidden by the shadow of the Earth, it is called Total Lunar Eclipse. If only a part of the Moon’s surface is covered by the shadow of the earth then it is called Partial Lunar Eclipse.
Solar Eclipse is formed when the Moon comes between the Sun and the Earth and the Moon’s shadow falls on the surface of the Earth. It occurs on a new Moon day.
If the sun is completely hidden by the Moon, it is called Total Solar Eclipse. If only a part of the Sun is hidden by the Moon. It is called Partial Solar Eclipse.
Artificial satellites are manmade objects which revolve around the Earth as the Moon does. These satellites are sent up in the rockets. They are used for various purposes such as w e a t h e r f o r e c a st i n g, communication etc.
History of Satellites:
The world’s first artificial satellite is the SPUTNIK-I was launched in 1957 by RUSSIA, but first active satellite was launched in 1962 named TELSAT.
India has launched 72 (as of 5 November 2013) Satellite up to till now but first satellite that was launched and used for communication purpose in INDIA was – ARYABHATTA (19TH April 1975)
- In 2011 ISRO launched First Indian nano satellite with the help of IIT Kanpur Named as JUGNU.
- Recently (5th November 2013) India has launched a Satellite for Mars Mission named as Mangalyaan Mission.
- The first geostationary communication satellite was –STNCOM 3 (19th August 1963)
- Father of geostationary communication satellite is –HAROLD ROSEN (Aircraft engineer)
Uses of Satellite
- Communication Satellites are used to relay television and radio programmers, for eg. INSAT-3E.
- Weather Satellite take pictures of the movement of clouds.
- They are helpful in forecasting the weather.
- They can give early warnings of dangerous storms or cyclones.
Thing of Remember
- Except Mercury and Venus all planets of our Solar System have their natural satellites. Earth has only one natural satellite called Moon.
- The heavenly bodies are Star, Planets, Asteroids, Meteors and Meteorites etc.
- The surface of the Moon as there is no air and water.
- There is no life on the Moon as there is no air and water.
- Lunar eclipse is formed when the Earth comes between the Sun and the Moon.
- Solar eclipse is formed when the Moon comes between the Earth and the Sun.
- Artificial Satellites are put in the orbits around the Earth. They help in Weather forecasting and Communication etc.