Solar System and The Universe | Geography | General Knowledge

Important Facts of Solar System and Universe

  • “Light Year” and “Parsec” are the unit of- Distance
  • 1 Light Year = ‎9.4607×1012 km
  • 1 Parsec = 3.26 Light Years
  • Nearest Star to earth- Alpha Centauri
  • Cosmology is the branch of astronomy in which we study the origin and evolution of the universe.
  • Our Sun belongs to the Milky Way Galaxy(Akash Ganga).
  • Milky Way Galaxy is the Spiral type of galaxy.
  • Constellation is a group of stars that appears to form recognizable shapes or pattern.
  • Stars have the light of their own. They are made up of vast clouds of gases like Helium, Hydrogen, etc.
  • Protostar is a highly condensed cloud of gases like Hydrogen and Helium.
  • A Black Hole is a region of space with a very strong gravitational field that even light cannot escape from its surface.
  • Sun is the nearest star to the Earth at a distance of 149,597,870 km
  • Sunlight takes approx 8 minutes and 20 seconds to reach the Earth’s surface.
  • The second nearest star to the Earth is Alpha Centauri.
  • The photosphere is the glowing surface of the Sun.
  • The chromosphere is the layer above the photosphere.
  • The Corona is the outer atmosphere of the Sun. It is the aura of plasma that surrounds the Sun.
  • Dark (absorption) lines in the spectrum of the Sun or other star is known as Fraunhofer lines.
  • The outwards emission of large, bright, gaseous features from Sun is known as Prominence.
  • The temperature of the core of the Sun is about 15 million degrees Celcius.
  • The circumference of the moon is about 11000 km.
  • Gravity on the moon’s surface is approx 1/6th of the Earth’s gravity.
  • The average distance from the Earth to the Moon is about 384,400 km.
  • In one revolution of Earth, the moon takes 27 days, 7 hours, and 43 minutes.
  • The moon doesn’t have the light of its own.
  • The reflected light of the Sun from the Moon reaches the Earth in 1.3 seconds.
  • Neil Armstrong landed on the moon on 21 July 1969.
  • There is no atmosphere on the moon.
  • Earth takes almost 365 days and 6 hours to complete an orbit of the Sun.
  • Earth is also called the Blue Planet.
  • Perihelion is the nearest position of the Earth in the orbit of the Sun- 3 January.
  • Aphelion is the farthest position of the Earth in the orbit of the Sun- 4 July.
  • The nearest planet to the Earth is Venus.
  • The Earth revolves around the Sun at a speed of 29.8 km/s.
  • The Earth completes a revolution along its axis in around 24 hours( 23 hours, 56 minutes, and 4 seconds).
  • Tides are the rise and fall of levels of sea levels.
  • Tides are occurred due to the effect of Gravitational Forces exerted by the Moon and the rotational force of the Earth.
  • The eight planets of our solar system are:
    • Mercury
    • Venus
    • Earth
    • Mars
    • Jupiter
    • Saturn
    • Uranus
    • Neptune
  • Pluto is considered as a Dwarf Planet.
  • The 5 Dwarf Planets of our solar systems are:
    • Pluto
    • Ceres
    • Eris
    • Makemake
    • Haumea
  • Increasing order of Planet’s distance from the Sun:
    • Mercury => Venus => Earth => Mars => Jupiter => Saturn => Uranus => Neptune
  • Increasing order of Planet’s diameter from the Sun:
    • Mercury => Mars => Venus => Earth => Neptune => Uranus => Saturn => Jupiter
  • Saturn has maximum number of satellites.
  • Venus has the same period of rotation and revolution.
  • Earth and Mars have almost the same rotation time along their axis. Mars rotation time along its axis is 24 hours, 39 minutes, and 35 seconds.
  • Earth rotates eastward around its axis. 
  • Jupiter is the biggest planet.
  • Venus is the brightest planet.
  • Mars is also known as the Red Planet.
  • Venus rotates from East to West.
  • Venus is also called Earth’s twin.
  • Venus is also known as the Morning and Evening star.
  • Uranus rotates from North to South.
  • Saturn and Uranus are known as the planets with ring.
  • Planet revolves around the Sun in an Anti-clockwise direction.
  • Venus is the nearest planet of the Earth.
  • Venus is the hottest planet.
  • Satellite of the Mars:
    • Phobos
    • Deimos
  • IDL: It stands for International Date Line
  • IDL is an imaginary line on the surface of the Earth that runs from north pole to south pole.

Important Facts:

  • There are 8 planets in our solar system.
  • Planets are revolving around Sun in elliptical orbits.
  • Sun rays take approx 8 minutes 16 seconds to reach the Earth.
  • The name of our galaxy is Milky Way.
  • Pluto is a dwarf planet.
  • The nearest planet to the Sun is Mercury.
  • Farthest planet to the Sun is Neptune.
  • The smallest planet among all the eight planets in our solar system is Mercury.
  • The largest planet among all the eight planets in our solar system is Jupiter.
  • Saturn is the second-largest planet in our solar system.
  • Uranus is the third-largest planet in our solar system.
  • Aura of plasma that surrounds the sun is called CORONA.
  • Major gases that the sun contains are Hydrogen and Helium.
  • Major gases that the sun contains are Hydrogen and Helium.


  1. The closest planet to the Sun.
  2. Orbits the Sun quickest.
  3. No significant Atmosphere.
  4. No natural satellites.


  1. Hottest planet.
  2. Known as Earth’s Twin.
  3. Longest rotation period.
  4. The dense atmosphere of gases.
  5. Revolves around the Sun from East to West.
  6. Only Venus and Uranus rotate from East to West.
  7. It is also known as the ‘Morning Star’ and ‘Evening Star’.
  8. No natural satellite.


  1. Earth’s atmosphere contains Nitrogen(78%), Oxygen(21%), Carbon-Di-Oxide, Argon, etc. gases.
  2. Earth takes approx 24 hours to rotate on its own axis.

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