(3753) Cruithne - SpeedyLook encyclopedia

(3753) Cruithne is a Astéroïde geocroisor approximately 5 km in diameter. Its orbit related to that of the Earth sometimes made it call the “second moon of the Earth” although it is not a satellite of this one.

Discovered

Cruithne was discovered the October 10th 1986 by Duncan Waldron on a photograph taken by the telescope Schmidt of the Observatoire of Siding Spring to Coonabarabran in Australia. It was also detected in 1983 (under designation 1983 UH) by Giovanni de Sanctis and Richard Mr. West of the southern European Observatoire with the Chile. Its unusual orbit was not given before 1997, by Paul Wiegert and Kimmo Innanen, of the Université of York to Toronto, and Seppo Mikkola, of the Université of Turku in Finland.

The asteroid bears the name of the Cruithne S which lived the Scotland and of the parts of the Ireland between 800 av. J. - C. and 1000; the name refers perhaps more specifically to their legendary first chief, also named Cruithne. He decides “crouigne more or less” ( /ˈkrɪhnʲə/ in Irish).

Dimensions and orbit

Cruithne makes approximately 5 km in diameter. It is located on a normal elliptic orbit around the Sun, with a orbital Period almost equal to that of the Earth. Cruithne traverses its elliptic orbit in a little less than one year, practically approaching until the orbit Mercure and moving away beyond that from Mars. From the point of view of a terrestrial observer, Cruithne describes a trajectory resembling a kind of bean, a loop around the Point of Lagrange L₄. With nearest, Cruithne is distant Earth of approximately 12 million km (30 times the distance the Ground-Moon); with further, the angle Ground-Sun-Cruithne reached 120°.

Cruithne is in has normal Elliptic orbit around the Sun. The orbital period of Cruithne being very slightly smaller than that of the Earth, the “bean” shifts gradually, moving away from the Earth initially, passing on other side of the Sun before returning about up to the point of Lagrange L₅ in approximately 385 years. At this time there, the Earth and Cruithne carry out an orbital energy exchange (an effect of gravitational Appui), affecting the orbit of Cruithne of a little more than one half-million of kilometers (and that of the Earth of approximately 1,3 cm). The period of revolution of Cruithne becomes larger then than that of the Earth and the trajectory of the asteroid shifts again gradually, in the opposite direction. The phenomenon is repeated in the other direction 385 years later, racourcissant the period of revolution of Cruithne in order to carry out the process again. All in all, Cruithne thus describes a Orbite in iron-with-horse from the point of view of the Earth.

Although it is thought that the orbit of Cruithne is not stable on the long run (with more: 5000 years), it is possible that it is in this configuration of orbital Résonance since: 100000 years. Cruithne approached with more close to the Earth in 1902, will be again close towards 2292 but other side to the iron-with-horse, then once again towards 2676.

There exists any collision risk between Cruithne and the Earth, the two bodies never approaching with less than 12 million kilometers. Cruithne is never visible with the naked eye at any place of its orbit.

Similar objects

Several other objects located on orbits in resonance similar to that of Cruithne for summer have found, among which, (10563) Izhdubar, and. and have an orbit whose average position follows a curve which evolves/moves between the shape of a horseshoe and that of a Quasi-satellite.

Janus and Épiméthée, two natural satellites of Saturn, also evolves/moves according to horseshoe orbits. These orbits are simpler than that which Cruithne follows but follow the same principles.

Many a Trojan asteroids was detected around the points of Lagrange of several bodies (primarily Jupiter, but also Mars, Neptune and the certain Saturn moons) but any of these bodies does not follow a horseshoe orbit.

See too

Internal bonds

External bonds

References

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