The sun in the solar system
The Solar System consists of the sun, the eight planets and their satellites (or moons), and thousands of other smaller heavenly bodies such as asteroids,comets and meteors.
- The sun in the centre of the solar system and all these bodies are revolving around it.
- The gravitational pull of the sun keeps all the planets and other objects revolving round it. Thus, the motion of all the members of the solar system is governed mainly by the gravitational force of the sun.
- In the solar system the planet nearest to the sun is Mercury and the planet farthest from the sun is Neptune now (not Pluto).
- The size of solar system has been estimated to be about 10 A.U.
- The solar system is dominated by the sun and the sun accounts for almost 99.9% of the matter in the whole solar system.
- The sun is also the source of all the energy in the solar system.
Members of the Solar System
- 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 about 6000 C.
- The temperature at the center is around 15,000,000 C.
- Shining surface of the sun is called photo sphere,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 Corona graph).
- The planet travel 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 km away from the Earth.
- Light (at the speed of 300,000 km per second) Lakes about 8.5 minutes to reach the Earth from the sun.
- 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, Jupiter , Saturn, Uranus , Neptune.
- The sequence of planets according to their size (in discending 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. “ Terestrial planets `and “jevian planets` are the two groups of planets.
- The four nearest planets to the Sun – Mercury, Venus, Earth and Mars are called terrestrial planets, because their structure is similar to the earth.
- Terestrial planets are classified in to inner and outer planets.
|Inner Planets||Outer planets|
|They include Mercury, Venus, Earth, Mars,||They include Jupiter, Saturn, Uranus Neptune etc.
|They are nearer to the sun.||They are far away from the sun.
|They are made up of dense metallic minerals.||They are made up of hot gases, mainly hydrogen and helium.|
|They move faster and have a shorter period of revolution.
|They move rather slowly and have a longer period of revolution.|
|They have thin, rocky crust.
They have a mantle rich in iron and magnesium.
|They are all gaseous bodies .(made of gases).|
|They have a core of molten metals.
|They have ring systems around them.|
|They have thin atmosphere.
|They have very few natural satellites (or moons) or no satellites.
|They have a large number of natural satellites (or moons).|
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