Solar System: Sun and the Eight Planets - gk lokam

1 October 2019

Solar System: Sun and the Eight Planets

Solar System: Sun and the Eight Planets

Solar System

The sun, eight planets, satellites and some other celestial bodies known as asteroids and meteoroids  form the solar system.

 We often call it a solar family, with the sun as its Head.


<img src="" alt=" Solar system">

Origin of the name "Solar"

‘Sol’ in Roman mythology is the ‘Sungod’. ‘Solar’ means ‘related to the sun’. The family of the sun is, therefore, called the solar

The Sun

<img src="" alt=" sun in the Solar system">

The sun is in the centre of the solar system. It is huge and made up of extremely hot gases. 

 It provides the pulling force that binds the solar system. 

The sun is the ultimate source of heat and light for the solar system. 
But that tremendous heat is not felt so much by us because despite being our nearest star, it is far away from us. 

The sun is about 150 million km away from the earth.

Planets in the Solar System

There are eight planets in our solar system. 

In order of their distance from the sun, they are: 

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

An easy way to memorise the name of the planets in order of their distance from the sun is:


Orbits in the Solar system

  All the eight planets of the solar system move around the sun in fixed paths. These paths are elongated. They are called orbits. 

Mercury is nearest to the sun. It takes only about 88 days to complete one round along its orbit. 

Venus is considered as ‘Earth’s-twin’ because its size and shape are very much similar to that of the earth.

Till recently (August 2006), Pluto was also considered a planet. 

However, in a meeting of the International Astronomical Union, a decision was taken that Pluto like other celestial objects (Ceres, 2003 UB313) discovered in recent past may be called
‘dwarf planets.”

The Earth in the Solar system

<img src="" alt=" The Earth in the Solar system">

The earth is the third nearest planet to the sun.

 In size, it is the fifth largest planet. 

It is slightly flattened at the poles. That is why, its shape is described as a Geoid. 

Geoid means an earth-like shape.

Why life is only in Earth?

  • Conditions favourable to support life are probably found only on the earth. 
  • The earth is neither too hot nor too cold. 
  • It has water and air, which are very essential for our survival. The air has life-supporting gases like oxygen. 

Because of these reasons, the earth is a unique planet in the solar system.

 Why Earth appears blue from the Outer Space?

From the outer space, the earth appears blue because its two-thirds surface is covered by water. It is, therefore, called a blue planet.

The Moon

<img src="Moon-gk-lokam-in.jpg" alt=" The moon in the Solar system">

Our earth has only one satellite (natural satellite), that is, the moon. 

Its diametre is only one-quarter that of the earth. It appears so big because it is nearer to our planet than othe celestial bodies. 

The Moon is about 3,84,400 km away from us. 

The moon moves around the earth in about 27 days.

 Why only one side of the moon is visible from Earth?

It takes exactly the same time to complete one spin. As a result, only one side of the moon is visible to us on the earth.

 Why there is no life in Moon?

The moon does not have conditions favourable for life. It has mountains, plains and depressions on its surface.

What is called a Satellite?

A Satellite is a celestial  body that moves around the planets in the same way as the planets move around the sun.

Artificial Satellite /Human-made Satellite

A Human-made Satellite  is an artificial body. It is designed by scientists to gather information about the universe or for communication. 

The Artificial Satellite is carried by a rocket and placed in the orbit around the earth. 

Some of the Indian satellites in space are INSAT, IRS, EDUSAT, etc

What are Asteroids?

<img src="the-asteroid-gklokam-in.jpg" alt=" The moon in the Solar system">

Apart from the stars, planets and satellites, there are numerous tiny bodies which also move around the sun. These bodies are called asteroids. 

Asteroids are found between the orbits of Mars and Jupiter 

Scientists are of the view that asteroids are parts of a planet which exploded many years back.


<img src="" alt=" The meteroids in the Solar system">

The small pieces of rocks which move around the sun are called meteoroids. 

Sometimes these meteoroids come near the earth and tend to drop upon it. 

During this process due to friction with the air they get heated up and burn. It causes a flash of light.

 Sometimes, a meteor without being completely burnt, falls on the
earth and creates a hollow.

What is called a Galaxy?

 A galaxy is a huge system of billions of stars, and clouds of dust
and gases. There are millions of such galaxies that make the Universe. 

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