🌍 The Planets of the Solar System The solar system has eight planets that orbit the Sun. Each planet is different in size, temperature, and composition. Mercury is the closest planet to the Sun. It is very hot during the day and very cold at night. Venus is the hottest planet. It has a thick atmosphere and is sometimes called Earth’s twin because of its size. Earth is the only planet known to support life. It has water, air, and a suitable temperature. Mars is called the Red Planet because of its red color. Scientists believe it once had water. Jupiter is the largest planet in the solar system. It has a big red storm called the Great Red Spot. Saturn is famous for its beautiful rings made of ice and rock. Uranus rotates on its side and is very cold. It has a blue-green color. Neptune is the farthest planet from the Sun. It is very cold and has strong winds.