They are basically the remains from the formation of the solar system. Asteroids are small, rocky objects that orbit the sun. The largest planetesimals became the planets and moons, while the smallest ones became the asteroids and comets.

The Short Answer: Asteroids are small, rocky objects that orbit the Sun. They did not grow in size into a planet because the strong gravity of Jupiter stirred them up. Asteroids are leftovers from the formation of our solar system about 4.6 billion years ago. Although asteroids orbit the Sun like planets, they are much smaller than planets. Most of the asteroids, made up of metal and rock, formed in the asteroid belt, and most of the comets, composed primarily of ices, ended up in the more distant Kuiper Belt and Oort Cloud. Asteroids were formed just like the other planets of our solar system- from gas and dust. Asteroids are formed from the leftovers of the formation of our solar system from about 4.6 billion years ago. A close-up image of the asteroid Ida taken by NASA's Galileo spacecraft. Asteroids are leftovers from the formation of our solar system about 4.6 billion years ago. Most scientists agree that all of the asteroids are the result of the the big bang. Early on, the birth of Jupiter prevented any planetary bodies …

Most of the asteroids in the Main Belt are made of rock and stone, but a small portion of them contain iron and nickel metals.

Asteroids are formed from the same dust and gas that formed the sun and the planets in our solar system by sand and dust in space and rocks How asteroids are formed? Early on, the birth of Jupiter prevented any planetary bodies from forming in the gap between Mars and Jupiter, causing the small objects that were there to collide with each other and fragment into the asteroids seen today. Early on, the birth of Jupiter prevented any planetary bodies from forming in the gap between Mars and Jupiter, causing the small objects that were there to collide with each other and fragment into the asteroids seen today. Composition. Although asteroids orbit the sun like planets, they are much smaller than planets.