The solar system formed approximately 4.6 billion years ago from a cloud of gas and dust called the solar nebula.The sun is the largest object in the solar system, accounting for 99.86% of its total mass. It is also a star, classified as a G-type main-sequence star.There are eight planets in the solar system, listed in order from the sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.Pluto was once considered the ninth planet in the solar system, but it was reclassified as...