Asteroids are massive bodies which are not in orbit around the sun, and there are asteroids on our space battle games. It is neither planets nor satellites, unquestionable scientific advance the thesis of remainders discs not having gathered out of planets lasting their formation. Be careful not to confuse asteroids with comets because of their orbit. A meteorite,in contradiction with an asteroid, necessary has a collision with a planet.
Asteroids are sometimes visible at naked eyes because of the low intensity of light they emit. At the beginning asteroids were seen as stones rejected from the solar system.
.The first asteroid was discovered in the observatory of Palermo in Sicily in 1801. There is more than 230.000 asteroids discovered. Some bear names (name chosen by the discoverer) of others numbers.
Some asteroids belongs to the category of Géocroiseurs. They can have a collision with the Earth because their orbits are really close to our planet. But the Earth can't see a danger in asteroids, they start to burn when they arrive into our atmosphere.
But asteroids measuring more than 140 meters broad which fly at less than 7,4 million kilometers of the orbit of the Earth are considered as potentially dangerous. Today we count more than 900 asteroids included in the category of potentially dangerous for the Earth.