Solar System – General Knowledge

Solar System

Our solar system consists of the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, dwarf planets like Pluto, dozens of moons and millions of asteroids, meteoroids and comets. It has Sun and stars and many things bound to it by gravity.

The eight planets of the solar system are listed below as per their distance from the Sun.

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

Do you know?

  • The largest planet in the Solar system is Jupiter. 
  • The smallest plant in the solar system is Mercury


  • Mercury is the nearest planet to the Sun.
  • Mercury is also the fastest planet which has no satellite.
  • Mercury takes 88 days for completing its one revolution in its orbit around the Sun and takes 58.65 Earth days for completing its rotation (on its axis).


  • Venus is the Hottest Planet of our solar system.
  • Venus if is closest to the planet Earth.
  • Venus completes its rotation (on its axis) in 243 Earth days and completes its one revolution in 224.7 days (in its orbit around the Sun).
  • Like Mercury Venus also has no satellite.
  • Venus spins in the opposite direction of the spin of the Earth.
  • The planet Venus is named after the Roman goddess of Beauty.


  • Earth is the third planet from the Sun. Mass of the Earth is 5.98 x 1024 kg and its diameter is 12,756 km.
  • To complete its rotation (on its axis), Earth takes 23 hours, 56 minutes, and 40 seconds and completes its one revolution (in its orbit around the Sun) it takes 365.26 days.
  • Earth has an Escape Velocity of 11,200 m/s and Obliquity of 23.40.
  • Earth has Nitrogen (78%), Oxygen (20.95%), Argon (0.930%), and Carbon Dioxide (0.039%) as its major atmospheric component.
  • Earth has mean density of 5.514 g/cm3 and surface of 510,072,000 km2.
  • Earth has 281 K as mean surface temperature; the mean maximum surface temperature of Earth is 310 K whereas the minimum is 260 K.
  • Earth’s total surface area is 510,100,500 sq. km, out of this total area 295 is the land area which is 148,950,800 sq. km and 70.92% is the water area which is 361,149,700 sq. km.
  • The mean diameter of the Earth is 12,734 km, diameter at Equator is 12,755 km and at the poles it is 12,712 km.
  • The circumference of the Earth at the poles is 40,024 km and at Equator it is 40,075 km.
  • The total mass of the Earth is 5.98 x 1024 kg whereas its Equatorial radius is 6,377 km.
  • Earth has an approximate age of 4,500 million years.
  • The most abundant elements of the Earth are Silicon (15.6%), Iron (about 32.5%), Oxygen (29.8%) and Magnesium (13.9%).
  • The Earth is structured in three layers Crust, Mantle and Core (Outer core and inner core, which are fluid and solid layer respectively).
  • The uppermost layer of the Earth is Crust which shares 1% volume of the Earth, this layer is largely composed of rocks. The thickness of the Crust is from 5 km to 60 km and its density ranges from 2.7 to 3.
  • The most abundant elements of Crust are Oxygen (46.6%), Silicon (27.7%) and Aluminum (8.1%).
  • The Mantle is a layer located between the Crust and the (Outer) Core, this layer has a thickness of about 2885 km.
  • The Mantle shares approx. 83% of the volume of the Earth and 65% of the mass.
  • Mantle has a density of about 3.4 g/cm3.
  • The upper layer of Mantle is called as ‘Asthenosphere.’
  • The Crust and the upper part of Mantle jointly is called as ‘Lithosphere.’
  • The Core is largely composed of iron and nickel; and hence is called as ‘Nife’ (i.e. Nickel and Ferrous).
  • The Core shares approx. 16% of volume of the Earth and 30% of the mass.
  • Core has a thickness of about 3,400 km from the Mantle.
  • Core is categorized as outer core, which is a fluid/molten state and and inner core which is a solid state. Also, the inner core has a density of about 13 g/cm3.


  • Mars is called as the ‘Red Planet’ of our solar system. It has two satellites – Phobos (means fear) and Deimos (means terror).
  • Mars takes 24 hours, 37 minutes, and 30 seconds for completing its rotation (on its axis) and takes 687 days for completing its one revolution (in its orbit around the Sun).


  • Jupiter is the fifth planet from the Sun and is the largest planet in our solar system.
  • It takes 9 hours, 50 minutes, and 30 seconds for completing its rotation (on its axis) and takes 12 earth years for completing its one revolution (in its orbit around the Sun).
  • Venus was named after the king of the gods in Roman mythology.
  • The planet has 63 natural satellites some of the major ones are
    Callisto, Europa, Ganymede, etc.


  • Saturn is the 6th planet from the Sun and the largest planet after Jupiter in our solar system.
  • Saturn is unique and popular because of its spectacular rings, which are made of chunks of ice and rock. The rings system of the planet is comprises of a variety of separate particles that independently rotate in circular orbits.
  • Saturn takes 10 hours and 14 minutes for completing its rotation (on its axis) and takes 30 years for competing its one revolution (in its orbit around the Sun).
  • Saturn has total 47 satellites out of which Titan is the biggest satellite.


  • Uranus was the first planet found using a telescope. It was
    discovered by William Herschel in 1781.
  • Uranus is known as the “sideways planet” because it rotates on its side.
  • Uranus is an Ice Giant planet which is approx. four times larger than the Earth.
  • The planet has 27 known moons, the significant are Titania, Miranda, Ariel etc.
  • It is the seventh planet from the Sun which is at a distance of approx. 1.8 billion miles.
  • Like Saturn, Uranus also has rings, it has a system of 5 faint rings.
  • Uranus takes 16 hours for completing its rotation (on its axis) and takes 84 years for completing its one revolution (in its orbit around the Sun).


  • Neptune is eighth planet from the Sun and is the farthest planet of our solar system.
  • Neptune was discovered in 1846 by Berlin scientist J. G. Galle.
  • Neptune takes 18 hours for completing its rotation (on its axis) and takes 165 years for completing its one revolution (in its orbit around the Sun).
  • Neptune has 13 satellites, significant of them are ‘Nereid’ and ‘Triton.’

Until the year 2006, our solar system has nine planets including Pluto as the ninth planet, but in the year 2006, the International Astronomical Union
(IAU) categorized the ninth planet Pluto as the dwarf planet.


  • Asteroids, also known as small planets or planetoids, are the rocky debris largely found between the planets Mars and Jupiter. These are too small to have their own atmosphere (as shown in the following image).
  • The Asteroids revolve around the Sun, which varies from 3 to 10 years.
  • By the time, more than 450,000 Asteroids are discovered; the largest Asteroid is Ceres, which diameter is about 1,025 km.


  • Meteors, also popularly known as falling stars or shooting stars, are pieces of dust and debris from space that burn up in the atmosphere of the Earth. It is heated due to the collisions with air particles and normally is visible in the upper atmosphere.
  • When Earth moves through the orbit if an asteroid or through the dusty trail of a comet the many streaks of light seen in the sky are called as a meteor shower.
  • Meteoroids are the small rocky or metallic bodies seen in the outer space. Its size ranges from small grains to 1-meter-wide objects.


  • Comets are frozen leftovers from the solar system formation, which are composed of rock, dust and ices.
  • Comets range from a few miles to tens of miles wide. When they orbit closer to the sun, they get heated and spew gases and dust into a glowing head which is seen larger than a planet.


  • Moon is the only natural satellite of the Earth and is the brightest object in the sky after Sun.
  • The rotation time of moon on its axis and the revolution time (around the Earth) is same that is 27 days, 7 hours, 43 minutes, and 11.47 seconds.
  • Moon revolves around the Earth once in every 27.3 days, which is called as ‘Sidereal Month. It takes 29.5 days to return to the same point on the celestial sphere in reference to the Sun this motion is called as ‘Synodic Month.

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