Over four and a half billion years ago, the Sun, the planets, and Pluto were formed in the Solar System.
Not all planets were created in the same way. Each looks different and is unique from the others. Mercury, Venus, Earth, and Mars are considered the ‘rocky planets’ because they are closer to the Sun, smaller, and do not contain much water and ice. Jupiter, Saturn, Uranus, and Neptune are known as ‘gas planets’ because they are farther from the Sun, larger, and contain gases like hydrogen and helium.
The Sun was created by dust and gas. The radiation from the Sun blew away the leftover dust and gas that created the planets inside the solar nebula. The solar nebula is a disk that surrounds the Solar System. Because it is much farther away from the Sun, Pluto formed a little differently. Icy bodies containing rocky elements and frozen water collided with each other, thus creating Pluto and some comets.
Mercury, Venus, Mars, Jupiter, and Saturn were discovered before written records. More recently discovered planets include Uranus and Neptune. In 1781, Uranus was discovered by William Herschel. Neptune was discovered in 1846 by Urbain Leverrier and J.C. Adams. Scientists have now sent probes to all of the planets to examine them. Each decade, we seem to learn more and more about our solar system and all of the amazing features it has.
[Source: Children’s Atlas of the Universe]