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Our Solar System: Formation, Planets, Facts, And Questions

Our solar system consists of The Sun and everything that orbits around it, including planets, moons, asteroids, comets and meteoroids. Know about the Formation, Planets, Facts, And Questions related to the Solar System.

Our Solar System

Our solar system mainly consists of a big star known as The Sun and everything that revolves around it, including planets, moons, asteroids, comets and meteoroids. There are a total of 8 planets and 5 Dwarf planets with 200+ moons, thousands of comets and lakhs of asteroids present in the solar system. It is a part of the milky way galaxy which is spiral and forms the centre of it. Scientists have estimated that the edge of the solar system is about 9 billion miles (15 billion kilometres) away from the sun. Currently, our Solar system is the only one to support life so far but scientists are exploring interstellar space and other options for the latest findings. Check out the complete details about our Solar System including the planets, moons etc.

Why is it named the “Solar System”?

Our planetary system is located in the milky way galaxy with the Sun being at the centre. All the planets revolve around a big star named the sun. Hence, our planetary system is known as the Solar system as anything related to the Sun is called Solar.

Formation of the Solar System

Many scientists think that our solar system formed from a giant, rotating cloud of gas and dust known as the solar nebula. As the nebula collapsed because of its gravity, it spun faster and flattened into a disk. Most of the material was pulled toward the centre that resulted in the formation of the sun. Other particles within the disk collided and adhered together to form asteroid-sized objects named as planetesimals. Some of which combined to become the rocky surfaces named asteroids, comets, moons and planets. The solar wind from the sun was so powerful that it swept away most of the lighter elements, such as hydrogen and helium, from the innermost planets, leaving behind mostly small, rocky worlds. The solar wind was much weaker in the outer regions, however, resulting in gas giants made up mostly of hydrogen and helium forming the outermost planets.

Layers Of Atmosphere And Its Composition

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The sun

The sun is by far the largest object in our solar system. It contains 99.8 per cent of the solar system’s mass and is a hot ball of glowing gases. The gravity of the Sun holds the Solar system together keeping everything in its orbit. Planets orbit the sun in oval-shaped paths called ellipses, with the sun slightly off-centre of each ellipse. Without the Sun’s energy, there will be no life on earth.

The Planets of Solar System

There are eight planets in our Solar System that are revolving around the Sun in elliptical orbits. The closest four planets namely Mercury, Venus, Earth, and Mars are termed terrestrial planets, which means they have a hard rocky surface. The farthest four planets of solar system namely Jupiter, Saturn, Uranus, and Neptune are called gas giants. These planets are much larger and their surface is composed of gas elements (mostly hydrogen).

Planets Moons Time taken to complete one Spin on Axis
(One Earth Day)
Length of year Features
Mercury No moons 59 Earth days 88 Earth Days
  • Smallest Planet
  • No Rings
  • Closest to sun
Venus No moons 243 Earth days 225 Earth Days
  • Spins backwards
  • No rings
  • Hottest Planet
  • The longest day of any planet
Earth 1 Moon 24 hours 365 Days
  • No rings
  • Known as the Blue planet.
  • Perfect place for life
Mars 2 moons Over 24 hours 687 Earth Days
  • Known as ‘Red Planet’ because iron minerals in the Martian soil oxidize
  • No rings
Jupiter 75 moons 10 Hours 4,333 Earth Days
About 12 Earth years
  • The biggest and largest planet
  • Gas Giant
  • Has rings
  • Twice as massive as all other planets combined
Saturn 82 Moons 10.7 hours 10,759 Earth Days
29 Earth years
  • Most spectacular ring system with 7 rings
  • Gas Giant
  • Second Largest planet
Uranus 27 known moons 17 hours 30,687 Earth Days
84 Earth Years
  • Known as the “sideways planet” because it rotates on its side.
  • 1st planet found using a telescope.
  • Ice Giant planet
  • Has 13 known Rings
  • Rotates backwards
Neptune 14 known moons 16 hours 165 Earth years
  • Known as the “Windiest planet”
  • At least 5 main rings
  • Voyager 2 is the only spacecraft visited there.
  • Ice Giant
  1. Mercury

  • It is the nearest planet to the sun.
  • It is the smallest planet of our solar system.
  • It can be observed just before sunrise or just after sunset, near the horizon.
  • It takes only about 88 days to complete one round along its orbit.
  • Mercury has no satellite/moon of its own.
  • Fastest revolution time.
  • Extreme weather +400°C & –200°C.
  • Mercury is also known as the Roman God of Commerce.

2. Venus

  • It is the brightest planet in the night sky.
  • It is the hottest planet.
  • It is often called as a morning or an evening star although it is not a star.
  • Venus is considered as the ‘Earth’s-twin’ because its size and shape are very much similar to that of the earth.
  • Venus has no moon or satellite of its own.
  • It rotates from east to west while the Earth rotates from west to east.

3. The Earth

  • The earth is the 3rd nearest planet to the sun, it is the fifth-largest planet.
  • It is slightly flattened at the poles. Hence, its shape is described as a Geoid.
  • The Earth has only one moon.
  • It is known as the Blue Planet.

4. Mars

  • It appears slightly reddish due to the presence of iron oxides and, hence, it is also known as the red planet.
  • Mars has two small natural satellites or moons.
  • Nix Olympia is a mountain spotted in Mars which is 3 times higher than Mountain Everest.
  • The name of two Satellites are Phobos and Deimos.
  • It is also known as the Roman God of war.

5. Jupiter

  • Jupiter is the largest planet of the solar system.
  • The mass of Jupiter is about 318 times that of our Earth.
  • It rotates very rapidly on its axis.
  • It has faint rings around it.
  • It has 75 moons or natural satellites.

6. Saturn

  • Saturn appears yellowish in colour.
  • It is the second-largest planet of the solar system.
  • It looks beautiful because of the rings. It has 7 main rings.
  • It has 82 moons or natural satellites.
  • Saturn also has a large number of satellites.
  • It is the least dense among all the planets.

7. Uranus

  • It is called Green Planet because of the presence of Methane gas.
  • Like Venus, Uranus also rotates from east to west.
  • Uranus has five major moons: Miranda, Ariel, Umbriel, Titania, and Oberon. It has a total 27 moons.
  • It is also known as Ancient Greek God.
  • Known as the “sideways planet” because it rotates on its side.
  • 1st planet found using a telescope.

8. Neptune

  • It is the Coldest planet and the windiest planets.
  • There are 14 Satellites.
  • At least 5 main rings are present.
  • Voyager 2 is the only spacecraft visited there.
  • It is an Ice Giant.

Periodic Table: Elements, Groups, Properties And Laws

Dwarf planets

Dwarf planets are objects similar to planets in the Solar System, however, they are defined as not large enough to qualify to be named as a planet as they didn’t qualify “cleared their orbital region of other objects.” There are 5 known dwarf planets in the Solar System namely Pluto, Ceres, Eris, Haumea, and Makemake.

Comets

Comets are often recognised as dirty snowballs and consist mainly of ice and rock. When a comet’s orbit comes close to the sun, the ice in its central nucleus turns into gas that shoots out of the comet’s sunlit side, carried by the solar wind outward to form into a long tail.

Asteroid belt

The asteroid belt is a region between the planets Mars and Jupiter. In this region of Asteroid belt, thousands of rocky objects orbit around the Sun. They range in size from tiny dust-like particles to the dwarf planet Ceres.

Kuiper belt

The Kuiper belt is a region of thousands of small bodies that exist outside the orbit of the planets. Objects in the Kuiper belt consist of “ices” such as ammonia, water, and methane.

Facts About our Planet — the Earth

  •  Estimated age of the Earth : 4600 million years.
  • The Earth is 23½° tilted on its axis and thus makes 66½º angle with the plane of its orbit
  • It takes 365 days and 5 hours 45 minutes to revolve around the Sun.
  • Earth is known as the “watery planet” or the “blue planet” due to presence of a huge amount of water.
  • The earth has a protective blanket of ozone layer high up in its atmosphere to save life from harmful ultraviolet radiations coming from the sun.
  •  Mean distance from the Sun : 149,407,000 kms.
  •  Equatorial diameter : 12753 kms.
  •  Polar diameter : 12710 kms
  •  Equatorial circumference : 40,066 kms.
  •  Period of rotation : 23 hrs. 56 mts. 4.09 sec. (24 hrs.)
  •  Period of revolution : 365 days 5 hours 48 mts and 45.51 seconds. (365¼ days)
  •  Total area : 510,100,500 sq. kms.

Facts about Solar System

  • The Universe or the Cosmos consists of millions of Galaxies. A galaxy is a huge assemblage of stars held together by the forces of gravity.
  • Existence of galaxies beyond Milky Way was first demonstrated by Edwin Hubble in 1924. He proved that the galaxies are flying away from each other and that the farther they are, the faster they fly. This means that the universe is expanding like a balloon that is being blown up.
  • Our galaxy is the Milky Way Galaxy (or the Akash Ganga). It is spiral in shape. It consists of over 100 billion stars rotating and revolving about its centre. The nearest galaxy to ours is Andromeda.

  • The Big Bang Theory evaluates that 15 billion years ago, cosmic matter (universe) was in an extremely compressed state, from which the expansion was started by a primordial explosion. This explosion broke up the super-dense ball and cast its fragments far out into space, where they are still travelling at thousands of miles per second.
  • There are three general kinds of galaxies in the universe namely elliptical, spiral and irregular. The Milky Way is a spiral galaxy.
  • It takes our solar system about 230 million years to complete one orbit around the galactic centre.
  • Light Year: It is the distance covered by light in one year in vacuum at a speed of 3 105 km/s.
  • Astronomical Unit (A.U): It is the mean distance between the earth and the sun. One light-year is equal to 60,000 A.U.
  • Parsec: It depicts the distance at which the mean radius of earth’s orbit subtends an angle of one second of an arc. It is equal to 3.26 light-years. 
  • A star’s colour indicates the temperature of its surface. Blue colour denotes maximum temperature. Then comes yellow, then red, etc.
  • If the star is of the size of the sun, it becomes a White Dwarf. Their central density can reach up to 10 grams per cubic cm.
  • The brightest star outside our Solar System is Sirius, also called Dog Star.
  • The closest star of Solar System is Proxima Centauri (4.2 light-years away). Then comes the Alpha Centauri (4.3 light-years away) and Barnard’s Star (5.9 light-years away).

Important lakes of India: List of Largest Lakes of India

Questions Based on Solar System

Q1. Which planet is known as the ‘red planet’?
Ans: Mars
Q2. Which of the following is the largest of the inner planets?
Ans: Earth
Q3. Which planet is known as the Earth’s twin?
Ans: Venus
Q4. Which is the brightest planet and the hottest planet?
Ans: Venus
Q5. Which is the largest planet in our solar system?
Ans: Jupiter
Q6. Which is the fifth largest planet of the solar system?
Ans: Earth
Q7. If there is no sun the colour of the sky would be:
Ans: Black
Q8. The natural Satellite of Earth is: 
Ans: The Moon
Q9. The nearest planet to the Earth is:
Ans: Venus
Q10. Which is the planet having a maximum number of satellites? 
Ans: Saturn

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