Moon has mountains, plains and depressions on its surface which casts shadow on moon's surface and it appears as spots from the Earth.

The sun is huge and made-up of extremely hot gases. It is at the centre of solar system. It provides the pulling force that binds the entire solar system. Apart from this, the sun is the ultimate source of heat and light for the solar system. These are the reasons which make the sun the head of the solar family.

The ancient people determined directions during night with the help of stars. The Pole Star always remains to the same direction and indicates North direction.

The moon takes 27 days to complete a spin of the Earth which is similar to its time of one revolution and because of its revolution, we can see only one side of the moon.

(i) The planet moves around the sun while the star remains fixed.
(Ii) The planet doesn't have its own light and heat but stars have their own light and heat.
(iii) The planets are generally smaller in size than stars.

(i) Mars has two satellites.
(ii) There are eight planets in above picture.

Galaxy A galaxy is a huge system of billions of stars and clouds of dust and gases. There are millions of galaxies in the universe. These galaxies altogether make the universe.
Akash Ganga or Milky Way is the example of galaxy. It appears as a river of light flowing in the sky, .
Universe Universe is the combination of millions of galaxies. The size of universe is very difficult to imagine and scientists still are working on it to know more about the universe.

Satellite is a celestial body that moves around the planet in the same way as the planets move around the sun, A satellite may be artificial or natural.
Some of the planets have different number of satellites, Saturn has maximum number of satellites Artificial satellites are sent in the orbit of the Earth through rocket.
Planets move around the sun in fixed path (orbit). These paths are elongated, The various planets take different time to complete a round of sun depending upon the distance of particular planet from the sun.