Formation of the solar system. The solar system is the sun and all the objects that orbit it. Scientists are not sure how the solar system formed. However, several theories have been developed. One popular theory states that the solar system formed from a spinning cloud of gas and dust called a nebula.
Scientiste think that gravity caused the nebula to shrink, or contract, to form the sun. After the sun formed, the other objects in the solar system. This took many millions of years.
The sun contains more than 99.8 percent of the mass in our solar system. The planets make up ,ost of the rest mass.
A planet is a body in orbit around the sun. It must have enough mass to assume a riund shape and have an orbit that is clear of other bodies.