The family of the sun and its eight planets constitute the solar system. There are eight planets in our solar system. The sun is the central part of the solar system. The first four planets (Mercury, Venus, Earth, Mars) are called terrestrial planets as they are made up of rocks and metals. The other four planets (Jupiter, Saturn, Uranus, Neptune) are gaseous planets as they are made up of ice and gases. Mercury is the smallest planet. Venus is known as the hottest planet. Earth is known as a blue planet. Mars is called a red planet. Jupiter is the largest planet. Saturn is known as a ringed planet. Neptune is known as a Windy planet.