![Animation of 2007 NS2 relative to Sun and Mars 1600-2500](https://upload.wikimedia.org/wikipedia/commons/d/d7/Animation_of_2007_NS2_relative_to_Sun_and_Mars_1600-2500.gif)
The Mars trojans are a group of
trojan objects that share the
orbit
In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...
of the
planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
Mars around the
Sun. They can be found around the two
Lagrangian point
In celestial mechanics, the Lagrange points (; also Lagrangian points or libration points) are points of equilibrium for small-mass objects under the influence of two massive orbiting bodies. Mathematically, this involves the solution of th ...
s 60° ahead of and behind Mars. The origin of the Mars trojans is not well understood. One theory suggests that they were primordial objects left over from the formation of Mars that were captured in its Lagrangian points as the
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
was forming. However, spectral studies of the Mars trojans indicate this may not be the case.
[ Another explanation involves asteroids chaotically wandering into the ]Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
Lagrangian points later in the Solar System's formation. This is also questionable considering the short dynamical lifetimes of these objects. The spectra of Eureka and two other Mars trojans indicates an olivine
The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...
-rich composition. Since olivine-rich objects are rare in the asteroid belt it has been suggested that some of the Mars trojans are captured debris from a large orbit-altering impact on Mars when it encountered a planetary embryo.
Presently, this group contains 14 asteroids confirmed to be stable Mars trojans by long-term numerical simulations but only nine of them are accepted by the Minor Planet Center
The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory.
Function
...
(†).
Due to close orbital similarities, most of the smaller members of the L5 group are hypothesized to be fragments of Eureka that were detached after it was spun up by the YORP effect (Eureka's rotational period is 2.69 h). The L4 trojan 1999 UJ7 has a much longer rotational period of ~50 h, apparently due to a chaotic rotation that prevents YORP spinup.
(''leading''):
* †
(''trailing''):
* 5261 Eureka
5261 Eureka is the first Mars trojan discovered. It was discovered by David H. Levy and Henry Holt at Palomar Observatory on 20 June 1990. It trails Mars (at the ) at a distance varying by only 0.3 AU during each revolution (with a secular t ...
(1990 MB) †
* †
* †
*
*
*
*
*
*
*
*
*
*
See also
* Trojan (celestial body)
In astronomy, a trojan is a small celestial body (mostly asteroids) that shares the orbit of a larger body, remaining in a stable orbit approximately 60° ahead of or behind the main body near one of its Lagrangian points and . Trojans can sha ...
* Minor planets that orbit near trojan points
** Earth trojan
An Earth trojan is an asteroid that orbits the Sun in the vicinity of the Earth–Sun Lagrangian points (leading 60°) or (trailing 60°), thus having an orbit similar to Earth's. Only two Earth trojans have so far been discovered. The name " ...
** Jupiter trojan
The Jupiter trojans, commonly called trojan asteroids or simply trojans, are a large group of asteroids that share the planet Jupiter's orbit around the Sun. Relative to Jupiter, each trojan librates around one of Jupiter's stable Lagrange poin ...
** Neptune trojan
Neptune trojans are bodies that orbit the Sun near one of the stable Lagrangian points of Neptune, similar to the Trojan (astronomy), trojans of other planets. They therefore have approximately the same orbital period as Neptune and follow rough ...
References
{{Portal bar, Solar System
4