[GS] [Geography] Solar System, The Sun & The Planets
Members of the Solar System
The Sun
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The Sun is at the centre of the Solar System.
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Its size is thirteen lakh times as that of the Earth.
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It is the nearest star to the Earth.
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It is an ultimate source of energy for life on Earth.
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Its diameter is 14 lakh Km.
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It is composed of 71% Hydrogen, 26.5% Helium and 2.5% other elements.
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Hydrogen and Helium are the main gases present in the Sun.
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Within the Sun, hydrogen is converted to Helium due to nuclear fusion releasing a tremendous amount of heat and light.
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It has a surface temperature of about 6000°C.
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The temperature at the centre is around 15,000,000°C.
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Shining surface of the sun is called Photo sphere, it appears like a disc, radiate energy and acts as a source of energy.
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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 Corona graph).
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The planet travels with the sun through millions of stars in our galaxy at a speed of about 70,000 km per hour.
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The Sun is about 150 million Km away from the Earth.
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Light (at the speed of 300,000 km per second) takes about 8.5 minutes to reach the Earth from the Sun.
The Planets
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These are opaque bodies which continuously revolve around and are lighted by the Sun.
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There are eight planets in the Solar system.
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A ninth planet has been recently discovered by NASA named as Carla.
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The sequence of planets according to their distance from the Sun is Mercury, Venus, Earth, mars, Jupiter, Saturn, Uranus, Neptune.
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The sequence of planets according to their size (in descending order i.e. form big to small ) is Jupiter, Saturn, Uranus, Neptune, Earth, Venus, mars, Mercury.
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Jupiter is the biggest and Mercury is the smallest planets of our system.
Classification of Planets
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The eight planets have been divided into two groups. All the planets of a particular group have some common feature. ‘Terrestrial planets’ or ‘Rocky planets and ‘Jovian planets’ or ‘Gaseous planets’ (Gas giants) are the two groups of planets.
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The four planets nearest to the Sun – Mercury, Venus, Earth and Mars are called terrestrial planes because their structure is similar to the earth.
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Other four planets – Jupiter, Saturn, Uranus and Neptune are Jovian planets.
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Planets are classified into the following two groups inner and outer planets. These are separated by asteroid belt.
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Pluto is a dwarf planet and its new name is 134340.