In our solar system, there is an invisible line around the Sun called the Frost Line. Outside of this line it is cold enough that materials with low boiling points like methane and oxygen, which are normally found as gases on Earth, can condense into solid material. These solid materials are called ices, much like when water freezes and forms water ice. If the ices were to be moved inside the Frost Line, the heat from the Sun would be too warm and they would sublimate, or turn from a solid into a vapor.
An Italian monk, Giuseppe Piazzi (1746-1846), discovered a faint, nomadic object through his telescope in Palermo, correctly believing it to lie in the orbital region between Mars and Jupiter where Kepler registered a gap in his harmonic scheme.
This demotion of a planet is not new. Ceres was discovered in 1801 and was awarded the status of a planet, but as many more asteroids started to be located, then it was demoted again. New astronomical advances have similarly shown many large objects beyond Pluto, and scientists began questioning whether Pluto, which is minute in relation to the gas giants Uranus and Neptune, should really be a planet.
NASA's orbiting Spitzer Space Telescope has found evidence of a massive asteroid belt around a "twin" of our own sun.
Kim Weaver, a Spitzer Space Telescope scientist, said the finding marks "the first time that scientists have found evidence for a massive asteroid belt around a mature, sunlike star."
Collisions in the asteroid belt do not happen as frequently today as they did in the early years of our solar system, only about once every 100,000 years (Bennett et al., 2008). This explains why there are many small bodies in the asteroid belt, but it does not explain why one big planet like the Earth or Mars didn’t form instead.
In a letter to a fellow astronomer, he put forth the first theory of asteroid origin. He wrote, “Could it be that Ceres and Pallas are just a pair of fragments…of a once greater planet which at one time occupied its proper place between Mars and Jupiter?”
The competing gravitational influence of Jupiter and the Sun did not allow the bits and pieces of the asteroid belt to accrete into a larger planet. Further, scientists see asteroids orbiting within the belt in concentric clusters, a phenomenon that also can be explained by taking into account Jupiter’s gravitational power.
The planets were subsequently dragged into their present positions by the gravity of large objects ejected from the Kuiper belt, a ring of icy debris lying beyond the planets. Once the Kuiper belt was depleted of large objects, the planets settled into their current orbits.
The asteroid belt, sometimes called the main belt, is situated between the orbits of Mars and Jupiter. this region is crowded with small rocky bodies called asteroids. The largest of these bodies: Ceres, Vesta, Pallas, and Hygiea have diameters larger that 400 km (248 miles).