Saturday, 10 November 2012

The solar system

The Solar System

The Constituents of the Solar System
The Solar System consists of eight planets and the Sun. The other members of the Solar System are natural satellites, asteroids, comets and meteoroids. The eight planets in the Solar System beginning with the nearest to the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. All the eight planets are moving around the Sun each following its own oval path called orbit.  On August 24, 2006, the International Astronomical Union (IAU) formally downgraded Pluto from an official planet to a dwarf planet.  The time taken for a planet to complete one revolution around the Sun is different from the time taken for another planet to do so. 


Mercury is the closest planet to the Sun. Since Mercury is closest to the Sun its temperature can be over 300oC in the daytime. Mercury rotates on its own axis very slowly, making one full rotation every 59 Earth days.


Venus is the second planet from the Sun. The size of Venus is about the same as that of the Earth. The planet is always covered by a very thick cloud of carbon dioxide and acid vapour. Thus, the temperature of Venus is extremely hight, even though Venus is twice as far from the Sun as Mercury and receives only a quarter as much light. As a result, the surface temperature can be above 450oC. Venus takes about 225 days to revolve around the Sun. It rotates on its own axis once every 243days. Its gravity is the same as that of the Earth.

Earth is the third planet from the Sun. It is the fifth largest planet. It is the only planet with oxygen and water. Thus, it is the only planet on which living things can survive and grow. Earth takes about 365 days to revolve around the Sun and rotates on its own axis once every 24 hours. Earth has a natural satellite (the Moon) revolving around it.


Mars is the fourth planet from the Sun. It also known as the Red Planet because it surface is being covered with red dust. Mars is a cold and lifeless planet. One revolution of Mars around the Sun takes 687 days.


Jupiter is the largest planet in the Solar System. It is the fifth planet from the Sun. Most of Jupiter’s volume is made up of gases and ice with only a small rocky core. The atmosphere is composed of mainly hydrogen in gaseous and liquid forms together with helium, methane and ammonia. Jupiter has sixteen natural satellites or moons and takes about 12 years to revolve once around the Sun.


Saturn is the sixth planet from the Sun. It is surrounded of a system of rings which make it the most striking and beautiful planet when viewed through a telescope. Saturn is the second-largest planet in the solar system. However, it is lighter than a body of water of the same size. Saturn is thought to have a small, rocky high-temperature core surrounded by ice and ammonia, mixed with grit and gases.The time taken for Saturn to revolve around the Sun is around 29 years. 


Uranus is the seventh planet from the Sun in the solar system. This planet is blue because it has cold gases, mainly made up of hydrogen and helium. Uranus also has a ring around it but the ring cannot be seen clearly because it is too thin and dim. It has five moons, and it rotates on its own axis slightly more slowly than Saturn. The time taken for Uranus to revolve around the Sun is around 84 years.


Neptune, the eighth planet from the Sun is almost the twin of Uranus. It is a little heavier than Uranus and is very slightly bigger. It is bluish-green.Neptune consists mainly of ice with some rocks and gases, and has less atmosphere. It has two moons and takes about 165 years to revolve once around the Sun.