Members of the Solar System

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The Sun

» The Sun is at the center of the Solar System.
» Its size is thirteen lakh times as that of the Earth.
» It is the nearest star to the Earth.
» It is an ultimate source of energy for life on Earth.
» Its diameter is 14 lakh kms.
» It is composed of 71% Hydrogen, 26.5% Helium and 2.5% other elements.
» Hydrogen and Helium are the main gases present in the Sun.
» Within the Sun, hydrogen is converted to Helium due to nuclear fusion releasing a tremendous amount of heat and light.
» It has a surface temperature of 5778 K or 5504.85°C.
» The temperature at the centre is around 15,000,000°C.
» Shining surface of the sun is called photosphere, it appears like a disc, radiates energy and acts as a source of energy.
» The outer layer of sun's atmosphere made up of thin hot gases, is called Corona. Corona is visible only during a total eclipse of the sun (or with a special solar telescope called Coronagraph).
» The planet travels with the sun through millions of stars in our galaxy at a speed of about 70,000 km per hour.
» The Sun is about 150 million kms away from the Earth.
» Light (at the speed of 3,00,000 km per second) takes about 8.5 minutes to reach the Earth from the Sun.

The Planets

» These are opaque bodies which continuously revolve around and are lighted by the Sun.
» There are eight planets in the Solar system.
» A ninth planet has been recently discovered by NASA named as Carla.
» The sequence of planets according to their distance from the Sun is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
» The sequence of planets according to their size (in descending order i.e. from big to small) is Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury.
» Jupiter is the biggest and mercury is the smallest planets of our solar system.

Classification of Planets

» The eight planets have been divided into two groups. All the planets of a particular group have some common features. 'Terrestrial planets' or 'Rocky planets' and 'Jovian planets' or 'Gaseous planets' (Gas giants) are the two groups of planets.
» The four planets nearest to the Sun-Mercury, Venus, Earth and Mars are called terrestrial planets, because their structure is similar to the earth.
» Other four planets—Jupiter, Saturn, Uranus and Neptune are called Jovian planets.
» Planets are classified into the following two groups inner and outer planets. These are separated by asteroid belt.:

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