Almost 3/4 of a century had no idea that not all the asteroids move between the orbits of Mars and Jupiter. But early in the morning of June 14, 1873 James Watson at the Observatory Ann arbor (USA) discovered the asteroid 132 Aarto. This object was able to track only three weeks, and then lost it. However, the results of determination of the orbit, though inaccurate, convincingly showed that the perihelion Aarti is inside the orbit of Mars.

On the asteroids, which would be closer to the Earth's orbit, remained unknown until the end of the XIX century, Now their number exceeds 80.

The first asteroid near the Earth was opened only on August 13, 1898 In this day Gustav Witt at the Observatory Urania Berlin has detected a faint object, quickly moving among the stars. High speed testified to his unusually close to the Earth, and the faint glitter of the close of the subject - an extremely small sizes. It was 433 Eros, the first asteroid baby a diameter of less than 25 km In the year of its opening it was at a distance of 22 million kilometers from Earth. Its orbit was not like any previously known. Perihelion it almost touched the Earth's orbit (q=1,46 a. e.) and it was so small in size (a=1,46 a.e.), the aphelion not reached rings of asteroids (q"=1,78 a. e.).

13 years later, on 3 October 1911, Johann Palisa in Vienna, opened 719 albert, who could come to Earth almost as close as Eros (q=1,19 a. e.). Almost in the same orbit Max wolf in Heidelberg in 1918 opened 887 the Alinda, and Walter baad the responsibility in 1924, in orbit slightly bigger - 1036 ganymed. In 1929 to these asteroids added 1627 Ivar and perihelion closer to the Earth than the Eros (q=1,12 a. e.) the aphelion, situated in the middle of a ring of asteroids (q"=2,60 a.e.).

March 12, 1932 the world, Delport at the Observatory in Uccle (Belgium) opened absolutely tiny asteroid orbit with a perihelion distance q =1,08 a. e. It was 1221 Cupid a diameter of less than 1 km, held at a distance of 16.5 million km from Earth.

Perhaps we, the inhabitants of the Earth, the most important to know the asteroid orbits are close to the orbit of our planet. Generally there are three families of near-Earth asteroids. They are named after a typical representatives of small planets: 1221 Amur, 1862 Apollo, 2962 Aton. To the family of the Amur river are the asteroids orbit which at perihelion almost touch the Earth's orbit. "Apollony" intersect the earth's orbit from the outside, their perihelion distance is less than 1 a. E. "Atonce" have orbits with large radius smaller than the earth and cross the earth's orbit from the inside. Representatives of all these families can meet with the Earth. As for the relatives of the transits, they happen often.

For example, an asteroid the Amur at the opening were 16.5 million kilometers from Earth, 2101 Adonis approached 1.5 million kilometers, 2340 Hathor - 1.2 million kilometers. Astronomers many observatories observed the transit by Land of asteroid 4179 Toutatis. on 8 December 1992, he was from us at a distance of 3.6 million kilometers.