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The Solar System-Know everything

Welcome Students, Let’s discuss about the solar system.

  • The solar system consist of the sun ,eight planets and their satellites and thousands of other smaller heavenly bodies such as asteroids, comets and meteors.
  • The Sun is at 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 the all members of the solar system is governed mainly by the gravitational force of the sun.
  • Planets revolve around the sun in elliptical orbit.
  • In the solar system planet nearest to the sun is Mercury and the planet farthest from the Sun is Neptune.
  • The Size of the solar system is estimated to at about 10^5 A.U.
  • The solar system is dominated by the sun which 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.
  • Pluto is a dwarf planet.
  • Mercury, Venus, Earth, Mars are called terrestrial planets and Jupiter, Saturn, Uranus, Neptune are called gaseous planets.

Memebers of the solar system

The Sun

  • The sun is at the centre of the solar system.
  • It is the nearest star to the earth
  • Its size is thirteen lakhs times as that of earth.
  • It is the ultimate source of energy for the life on earth.
  • Its diameter is 14 lakhs kms.
  • Its is composed of 71% hydrogen,26.5% Helium and 2.5% other elements.
  • 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 5778K or 5504.85 Celsius.
  • The temperature at the center of the sun is around 1.571 x 10^7 K or 15,000,000 Celsius.
  • 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 is made up of thin hot gases is called Corona. Corona is only visible during total eclipse of the sun or with a special 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 3,00,000km per second takes about 8.5 minutes to reach the Earth from the sun.

The Planets

  • These are the opaque bodies which continously revolve around and 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 the planet according to their distances from the sun is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
  • The Sequence of the Planet according to their size from big to small is Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury.
  • Jupiter is the biggest and Mercury is the smallest planet of our solar system.

Classification Of Planets in our Solar System

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” are two groups of the 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.

Inner PlanetsOuter Planets
They Include Mercury, Venus, Earth, Mars.They Include Jupiter, Saturn, Uranus, Neptune.
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 shorter period of revolutionThey move rather slowly and have a longer period of revolution
They have thin, rocky crustThey are all gaseous bodies
They have a mantle rich in iron and magnesium.Made of gases
They have a core of molten metalsThey have a ring system around them.
They have thin atmosphereNot available
They have very few natural satellites or no satellites They have a large number of satellites.
Classification of planets

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Some notable facts about various planets and satellites


  • Mercury is the closest planet to the sun.
  • It is extremely hot planet.
  • The Planet has no water on it.
  • Mercury planet has no gases like CO2,N2,H2 and O2 which can act as building block of life.
  • Mercury planet has no protective blanket like Ozone around it to prevent us from harmful radiations.


  • Venus is the second planet in distance from the Sun. This planet is nearest to the Earth and is also the brightest Planet.
  • Venus is known as “Evening star” as well as “Morning Star“.
  • Venus is Surrounded by thick Cloud cover hence known as “Veiled Planet“( Veil means unclear/cover).
  • Venus is like the Earth in size and mass, hence also known as the “Earth’s twin’.
  • It also rotates clockwise like Uranus.
  • Venus is the hottest planet( even hotter than Mercury) of our solar system due veil of cloud.
  • Venus has no water on it. There is no sufficient oxygen on the Venus.

The Earth

  • Earth is the largest of the inner planets.
  • The Earth is 23 and half degree tilted on its axis and thus makes 66 and half degree angle.
  • It takes 23 hours 56 minutes and 4.091 seconds to rotate on its axis.
  • It takes 365 days, 5 hours and 48 minutes to revolve around the Sun.
  • Earth is known as “Watery planet” or the “blue planet” due to the presence of huge amount of water on it.
  • Earth is the only known planet which provides sustenance or life on it. It has a large quantity of oxygen which supports life.

The Moon

  • The Moon is the only satellite of earth.
  • It has a diameter of 3,475 km and its circumference is 10,846 km while its orbit is elliptical.
  • The maximum distance of the moon from the earth is 4,06,000 km and the minimum distance is 3,64,000km.
  • It takes 27 days, 7 hours and 43 minutes to rotate on its axis and approximately the same period of time it takes to revolve around the earth. the moon’s period of revolution with reference to the sun is about 29.53 days (29 days, 12 hours, 44 minutes and 2.8 seconds).This period is called a synodic month.
  • Only 59 percent of the total surface of the moon is visible from the earth.
  • The bright part of the moon is full of the moon is full of mountains whereas the dark patches are low lying plains.
  • ‘Sea of tranquility made of the plain of dust particles, is on the rear side of the moon which always remains dark.
  • The highest mountain on the moon is liebuilty mountain which is 10,660 meter high.
  • The moon has no atmosphere, no twilight and no sound.
  • The temperature during daytime is about 100 degree C and during night it drops down to about -180 degree C.
  • The light from the moon takes 1.3 seconds to reach the earth.
  • The size of the Moon is one-fourth the size of the earth.
  • Gravitational pull of Moon is one-sixth that of the earth.
  • Mainly silicon, iron, magnesium etc elements are found on the Moon’s surface.
  • The study of the Moon is called Selenology.
  • Moon is also known as the fossil planet.


  • Iron-rich red soil and pink sky of Mars give it the name, ‘Red Planet’.
  • Phobes and demons are two satellites of mars.


  • Jupiter is the largest planet of the solar system.
  • Jupiter is also known as winter planet, as its average temperature is very low -148 degree celcius.
  • gannymeda , satellite of the jupiter is the largest satellite in the solar system.


  • Saturn is the second largest planet.
  • Saturn has bright concentric rings which are made up of ice and ice covered dust particles which revolves around it.
  • Titan is the largest satellite of saturn.


  • Uranus is about four times the size of earth. This planet appears greenish in colour because if methane gas present in its atmosphere.
  • Uranus was discovered in 1781 by sir William hersiel.
  • uranus is the 7th planet form the sun.
  • Uranus is the first planet to have been discovered by the use of a telescope.
  • Uranus is the third biggest planet of the solar system.
  • Uranus is extremely cold, having surface temperature -190 degree C and is surrounded by 13 rings namely zeta/R1986U2,6,5,4, alpha, beta, eta, gamma, delta, lambda, epsilon, nu, mu.
  • uranus rotates east to west on its axis, which is opposite to other planets except venus.
  • the axis of uranus has large inclination so that it appears to be lying down, hence it bears the name ‘A planet on its side’.


  • Neptune is the 8th planet of the solar system.
  • The temperature on the surface of neptune remains low.
  • Neptune is very similar to Uranus and can be considered as its twin.
  • Neptune is surrounded by methane rings of sub zero temperature.


  • On the basis of the new definition of planet given by the IAU (international astronomical Union) the worlds’s top institution on space science research, leading astronomers participating in IAU’s meet at Prague. on the August 24 ,2006, declared that pluto would no longer remain a planet.
  • Under the IAU’s new guidelines, the number of planets in the solar system has thus been reduced from nine to eight. its merits mentoring here that, prior to this decision, Pluto had been holding the planetary status since its discovery in 1930 by Clyde Tombaugh.
  • Now, With the omission of pluto from the solar system, its membership has been restricted to the eight classical planets namely mercury, venus, earth, Mars, jupiter, saturn, uranus and Neptune.

Frequently Asked Questions

How many Planets are there in our Solar System ?

There are 8 planets in Our Solar System. Now Pluto is not considered as a planet so there are only eight planets. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

What is the second planet from the sun?

Venus is the second planet from the sun. Planets according to the distance from the sun.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

Which is the hottest planet of our solar system ?

Venus is the Hottest Planet of our Solar System. Mercury is nearest planet to the sun but it has no atmosphere so the temperature of the mercury is high but not as high as Venus. Venus has large gas clouds which can trap lots of heat which increases the temperature of Venus.

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