Quasi-satellite

A quasi-satellite is a Celestial object which, seen since another body, seems to carry out a revolution around this one without to be technically in orbit around. It is thus about a companion more than of a reality Natural satellite.

Description

The quasi-satellites are a particular solution of the astronomical problem of the systems to three bodies. It thus relates to two objects in Révolution around a more massive third (generally a Planet and a Astéroïde around a star) but which however put as much time to traverse to them Orbite (orbital Résonance 1:1).

There exist many examples of resonance 1:1 in the Solar system, like the Trojan Astéroïdes placed at the points of Lagrange L4 and L5 of planet, or like (3753) Cruithne, asteroid companion of the Ground whose orbit appears to describe a horseshoe seen since the latter. However, unlike these bodies, the quasi-satellites seem to turn around planet that they accompany for an observer located on this one, achieving a kind of revolution in as much of time than one should not any for planet to do one around its star of them.

Formally, a quasi-satellite orbits around star and not around planet like a genuine satellite. Even if the asteroid remains relatively close to this one, it of it is too distant to be dependant Gravitation nellement. However, of disturbances gravitational have inflected its orbit so that, on the one hand, it turns around star in as much time than the planet (on an eccentric orbit more which is not inevitably located in the same plan) and, on the other hand, on an orbit whose main roads have about the same orientation as that of planet.

When the asteroid is with closest to star, it exceeds planet. As its orbit is eccentric, it slows down then and moves away and ends up exceeding the orbit of planet. Seen this one, all occurs like if, to the one year length, the asteroid turned little by little around, describing a trajectory which is not circular, nor even elliptic, but in the bean shape.

Stability

A quasi-satellite orbit is generally not stable. In the case of the Earth, the asteroids 2002 AA29 and 2003 YN107 are in this moment of the quasi-satellites, situation which should not last more than one ten years. Beyond, it will similarly take again an orbit in iron-with-horse (with (3753) Cruithne) and it is impossible to say with certainty if they will become again of the quasi-satellites at the end of a few centuries.

Studies showed that it would be possible with a theoretical quasi-satellite of Uranus or of Neptune to remain it for the lifespan of the Solar system with the help of certain conditions of eccentricity and Inclinaison. Such objects were however not discovered yet.

Examples

  • Venus:
    • 2002 VE68

  • Ground:

    • 2002 AA29
    • 2003 YN107
    • 2004 GU9

See too

Internal bonds

External bonds

  • '' Quasi-satellite Information Page ''

  • '' Earth' S New Companion Dolly: Quasi-satellite Discovered ''
  • '' Astronomy.com: With new " moon" for Earth ''
  • Discovered first Venus quasi-satellite

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