is a very small
asteroid and
near-Earth object
A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). ...
of the
Apollo group, approximately in diameter. Like , it is in a
co-orbital configuration
In astronomy, a co-orbital configuration is a configuration of two or more astronomical objects (such as asteroids, moons, or planets) orbiting at the same, or very similar, distance from their primary, i.e. they are in a 1:1 mean-motion resonance ...
relative to Earth moving in a 1:1
mean-motion resonance
In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relationsh ...
. It was first observed on 13 April 2001, by astronomers with the
LINEAR
Linearity is the property of a mathematical relationship ('' function'') that can be graphically represented as a straight line. Linearity is closely related to '' proportionality''. Examples in physics include rectilinear motion, the linear ...
program at the
Lincoln Lab's ETS near Socorro, New Mexico, in the United States.
has not been observed since its short four-day observation period in April 2001.
Description
With an
orbital period
The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...
of 369 days, is in a near 1:1
orbital resonance
In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relationsh ...
with
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
, and also has about the same orbit around the Sun as Earth.
Unlike most near-Earth asteroids that simply fly by when they approach Earth, the Earth catches up with this asteroid from behind so that the asteroid then pauses in the vicinity of Earth. While in the vicinity of Earth, the asteroid moves in a
helical
Helical may refer to:
* Helix, the mathematical concept for the shape
* Helical engine, a proposed spacecraft propulsion drive
* Helical spring, a coilspring
* Helical plc, a British property company, once a maker of steel bar stock
* Helicoil
A t ...
(corkscrew) pattern that resembles an orbit around the Earth, like the Earth has a new moon. But it is not really a moon, because the asteroid is not gravitationally bound to the Earth, and eventually the asteroid moves on away from Earth and continues its orbit around the Sun. was in this helical pattern from about 1997 to 2005, making the closest approach to Earth on 6 April 2001, and will not make another close approach until 2092.
The asteroid probably has a
horseshoe orbit, but this has not been proven because the orbit was determined from only 5 days worth of observation.
The
Jupiter Tisserand invariant
Tisserand's parameter (or Tisserand's invariant) is a value calculated from several orbital elements (semi-major axis, orbital eccentricity and inclination) of a relatively small object and a larger " perturbing body". It is used to distinguish dif ...
, used to distinguish different kinds of orbits, is 6.033.
Other asteroids that move in this helical pattern, some of which the Earth catches up with the asteroid, and others in which the asteroid catches up with Earth, are , , and .
See also
*
3753 Cruithne (1986 TO)
*
*
*
*
*
*
Orbital resonance
In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relationsh ...
References
External links
*
*
*
{{DEFAULTSORT:2001 GO2
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Minor planet object articles (unnumbered)
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20010413
Horseshoe orbit