Composition of the solar system

The study of heavenily bodies is known as Astronomy. The solar system is made up of the following:

  • The sun
  • The planets
  • Asteroids
  • Comets
  • Meteors
  • The moon

The sun

The sun is actually, a star.

It is a yellow-colored star of moderate size among the billions of stars in the Milky Way.

It rotates on its own axis in an anti – close wise direction.

Formed of very hot gases mainly hydrogen 70%.

The sun is a heated star. The temperature at the centre of the sun is about 150,000,000° Celsius and at the surface it is about 6,000° Celsius.

It is the source of light and heat of the earth but also of other planets and satellites. The earth would have been eternally dark without sun light.

The planets

Planet is a Greek word for wanderer or one who is constantly moving.

There are nine planets in the universe moving around the sun in the same direction.

The sun maintains a strong pull of gravity that keeps all the planets in their orbits.

The nine planets starting from the one nearest to the sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.

Facts about the planets

Mercury is the smallest while Jupiter is the largest. All the planets have moons moving around them except for Mercury and Venus.Asteroids are small bodies moving around the sun and occupy the spaces between the orbits.


  • The smallest and nearest planet to the sun.
  • It is about 579 000 000 km away.
  • Its revolution around the sun is 88 days, which is the length of a year in mercury.
  • The planet has a dense atmosphere of heavy inner gases
  • It has no satellite or moon.


  • It is twice the distance of mercury away from the sun, it is the next closest planet.
  • Venus is often considered as Earth’s twine because of their close proximity in size, mass
  • (weight) and density.
  • It is a hot planet and has a dense atmosphere of carbon dioxide.
  • It’s the earth twin planet because it is almost similar to the earth.
  • Its takes 243 earth days to take its rotation
  • It suffers from extreme greenhouse effect.


  • It has an atmosphere consisting of a mixture of gases.
  • Its surface temperature ranges from -50o to +50o
  • .Life is possible on this planet.
  • The Earth has 1 natural moon or satellite that revolves eastwards around the Earth once in every 28 days.
  • The Earth takes 365 1/4 days to revolve around the sun.


  • Referred to as the red planet because when observed from the earth using a telescope it always appears to be red in color.
  • It has two moons revolving around it.
  • It is smaller than Earth but it is believed by most professional astronomers to be the next planet after Earth to have the possibility of some plant life.


  • It is the fifth planet and the largest planet in the universe.
  • Rotates on its own axis at a very faster speed.
  • Keep on charging in color from time to time.
  • Has thirteen rings.
  • It is 773 million km away from the sun
  • Its surface is made of many gases like hydrogen, helium and methane.
  • It has 63 moons or satellites.
  • It is very cold due to its distance away from the sun.


  • It is the sixth planet and second largest.
  • It has three rings around it, the middle ring being the largest and brightest.
  • It has eight moons/planets.
  • It is 1,429 million km away from the sun.
  • It has three rings and 61 satellites around it.
  • It is so far from the sun that it takes 29 1/2 years to complete its orbit.


  • It was discovered in late 18th century.
  • It is another giant planet 50 times larger than Earth and 15 times as heavy.
  • Uranus has twenty-seven known satellites, the largest ones being Titania, Oberon,
  • Umbriel, Ariel and Miranda.
  • It has a greenish- bluish appearance.
  • It is tilted at an angle of 88o hence it rotates in a retrograde or backward manner.
  • Unlike other planets, Uranus orbits around the sun in a clockwise direction from east to west with five satellites revolving round it.
  • It has a faint equatorial ring discovered in 1979.


It is the eighth planet and very similar in size ,color and character to Uranus.

  • Neptune is the eighth and farthest known planet from the Sun in the Solar System.
  • The planet is named after the Roman god of thesea.
  • Neptune’s atmosphere is primarily composed of hydrogen and helium.
  • Neptune has thirteen known satellites.
  • It closely resembles Uranus .
  • It is very cold and it has blue appearance.


  • It is the farthest away from the sun.
  • The temperature is very cold.
  • Newly discovered.
  • It takes 248 years to complete its orbit due to distance from the sun.
  • It takes 6.4 days for its rotation
  • When it is near the sun (perihelion) and when it is farthest from the sun (aphelion) the
  • distance is 2766 million miles.


  • These are small planet-like objects also known as planetoids.
  • Minor member of the solar system
  • An asteroid is a small irregular shaped rocky body that revolves around the sun.
  • There are about 50,000 asteroids in the solar system.


These are heavenly bodies revolving around the sun in their own orbits with a head and a tail.


  • Meteors are small heavenily bodies that enter the earth’s atmosphere from the universe at very fast speeds.
  • A meteor is also a minor member of the solar system
  • It’s a bright trail of light that appears in the night sky.
  • It is also a shooting star
  • Meteors are caused by rocky objects from space called meteoroids.


These are meteors that pass through the atmosphere, fail to burn up and land on the surface of the earth as large rocks.