solar system

solar system, planets, planetary system-11111.jpg

Our planetary system is located in an outer spiral arm of the Milky Way galaxy. Our solar system consists of our star, the Sun, and everything bound to it by gravity – the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune; dwarf planets such as Pluto; dozens of moons; and millions of asteroids, comets, and meteoroids. Our solar system orbits the center of the Milky Way galaxy at about 828,000 km/h. It takes our solar system about 230 million years to complete one orbit around the galactic center.

The Solar System was formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. 99.86% of the Solar System’s mass is in the Sun and most of the  remaining mass is contained in the planet Jupiter.

 Name of
of known
of the axis
 Period of
 Period of
 MagnetismAtmosphere  Rings
 Mercury  0 0.001 58.65 day 88 earth days No No No
 Venus 0 177.2 243 day 225 earth days No Yes No
 Earth 1 23.4 24 hours 1 year (365 days 4 hour) Yes Yes No
 Mars 2 25.2 24 hours 37 min  1.88 earth years Yes Yes No
 Jupiter 64 3.1 9 hours 56 minutes  11.87 earth years Yes Yes Yes
 Saturn 33 26.7 10 hour 40 minutes ( 29 earth years Yes Yes Yes
 Uranus 27 97.9 17 hour 24 min  84 earth years Yes Yes Yes
 Neptune 13 28.8 16 hour 11 min  164 earth years Yes Yes Yes

The Sun

The sun which is at the center of the solar system is a yellow coloured star. The sun is a ball of hydrogen gas that radiates heat and light. It generates power by nuclear fusion; atoms are fused together and produce nuclear energy. Every second, the sun converts about four million tons of matter into energy.  Therefore sun surface temperature is around 6000° C.

The size of the sun is so huge that around 13 lakh planets of the size of the earth can be easily placed within it. Due to the gravitational force of the sun, the celestial bodies (planets) in the solar system revolve around it. The diameter of the sun is approximately 13,92,000 km. The sun rotates around its axis and while doing so, it revolves around the center of the Milky Way taking the solar system along with it.

The Planets : Terrestrial planets and (outer)Giant planets.

The eight planets in the solar system classified in two categories : terrestrial planets and (outer)giant planets. The terrestrial planets are the four innermost planets in solar system  – Mercury, Venus, Earth and Mars. These planets are primarily composed of silicate rock. These planets are called terrestrial because of their earthlike characteristics, especially their rocky composition.

The outer planets or gas planets are Jupiter, Saturn, Uranus and Neptune. These large planets mostly composed of frozen hydrogen and helium. They do not have solid surface.

Terrestrial planets:-

Mercury : This planet is closest to the sun. It is visible in the morning and the evening if it is away from the sun. A number of depressions, which look like volcanic craters, but are actually caused by meteoric falls can be seen on the surface of Mercury. Mercury is the fastest moving planet therefore its orbit the sun only 88 earth days, but it revolves on its axis very slowly that one murcurian day lasts 59 Earth days.


Venus : It is the brightest planet in the solar system. It is seen in the sky in the east before the sunrise and in the west after the sunset. It rotates around itself from east to west. It is the hottest planet. Venus has the dense atmosphere, composed by cloud of carbon dioxide. It shines luminously, making it the third brightest object in our sky after the sun and moon.


Earth : It is the third planet of the solar system. No other planet other than the earth has life on it. As the earth is a magnet, there is a magnetic field around the earth. It diverts the harmful rays from the sun towards the polar regions of the earth.


Mars : It is the fourth planet in the solar system. As the soil on Mars contains iron, its colour is reddish. Hence Mars is also called the Red Planet. The highest and longest mountain in the solar system ‘Olympus Mons’ is located on Mars.


The outer(giant) planets:-

Jupiter : It is inner most planet among the gas planets. This is the largest planet of the solar system. It is so huge that as many as 1397 planets of the size of the earth can get accommodated in it. Even though the planet is so huge, it revolves around itself with a great speed. As huge storms occur frequently on it, it is also called the ‘Stormy Planet’. It has a 63 orbiting moons.


Saturn : It is the sixth planet of the solar system and next only to Jupiter in size. It is considered to be a peculiar planet because of the rings around it. Though its mass is 95 times that of the earth, its density is very low. If it were dropped into a sea large enough to hold it; it would actually float in it! It is composed mostly with hydrogen and helium gas.


Uranus : It is the seventh planet in the solar system. It cannot be seen without a telescope. Its axis is so greatly inclined that it appears as if it is rolling along on its orbit. Uranus gets its blue-green glow from methane gas in its atmosphere and composed almost entirely of hydrogen and helium.


Neptune : It is the eighth planet in the solar system. A season on Neptune lasts for about 41 years. On this planet, winds blow with extremely high speed. Neptune has most extreme weather of any planet in the solar system. Neptune takes 164.8 Earth years to orbit the sun.

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