Solar System

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Solar System: the Sun and Eight Planets

The solar system comprises of the Sun and eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune), which is believed to have been developed from the condensation of gases and other lesser bodies.
The position of Sun is at the centre of solar system and all the eight planets revolve around the sun in elliptical orbit. Sun is the nearest star to the Earth.
The size of solar system has been estimated to about 10⁵ AU (1 Astronomical Unit = 149 597 871 kilometers).

Image credits: Wikimedia Commons

Components of the Solar System:

Our solar system consists of

• The sun, eight planets and their respective satellites.
• Five Dwarf Planets.
• Interstellar debris such as asteroids, meteoroids, Comets.
• The electrically charged gases, called Plasma. Interplanetary dust particles.

About the Sun:

• The sun accounts more than 99% of the total mass of the solar system and due to this reason Sun exerts immense gravitational pull to keep the planets rotating around it in definite elliptical orbit.
• The Sun is the major source of energy of the solar system. the energy is generated by nuclear fusion reaction, that converts hydrogen into helium in the core of the Sun.
• The glowing surface of the Sun that we see is called as Photosphere.
• The 2000 km layer deep above photosphere is called as Chromosphere.

Facts about the Sun:

• Main gases on the Sun are Hydrogen and Helium.
• Sun has a surface temperature of about 6000°C.
• Sun is one of the stars in the Milky Way Galaxy. It takes 224 million years to complete one circle (revolution) around the galactic circle called (cosmic year).
• The Sun is 109 times bigger than the Earth.
• Sunlight takes 8 minutes 16.6 seconds to travel from the Sun to the Earth.

About Planets:

• Eight Planets in solar system are opaque bodies, which continuously revolve around the in elliptical orbit and are lighted by Sun.
• The descending of planets according to their size is Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars and Mercury.
• The sequence of planets according to their distance away from the Sun is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Classification of Planets:

Planets can be classified into two types as: Inner planets and outer planets

Inner planets:

• Mercury, Venus, Earth and Mars are inner planets.
• These inner planets are called as Terrestrial or Rock planets.
• These inner planets are nearer to the Sun.
• They have very few natural satellites (or moons) or no satellites.
• These inner planets have core of molten metals.
• They move faster and have a shorter period of revolution.

Outer planets:

• Jupiter, Saturn, Uranus and Neptune are outer planets.
• These outer planets are far away from the Sun.
• They have a large number of natural satellites (or moons).
• They move rather slowly and have a longer period of revolution.