5261 Eureka
| Discovery | |
|---|---|
| Discovered by | David H. Levy and Henry Holt |
| Discovery date | 20 June 1990 |
| Designations | |
| Pronunciation | /jʊˈriːkə/ |
|
Named after
|
Eureka |
| 1990 MB | |
Martian L5 
|
|
| Orbital characteristics | |
| Epoch 13 January 2016 (JD 2457400.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 13267 days (36.32 yr) |
| Aphelion | 1.6222 AU (242.68 Gm) |
| Perihelion | 1.4249 AU (213.16 Gm) |
| 1.5236 AU (227.93 Gm) | |
| Eccentricity | 0.064766 |
| 1.88 yr (686.89 d) | |
|
Average orbital speed
|
24.11 km/s |
| 145.29° | |
| 0° 31m 26.76s / day | |
| Inclination | 20.280° |
| 245.057° | |
| 95.456° | |
| Known satellites | 1 |
| Earth MOID | 0.497052 AU (74.3579 Gm) |
| Jupiter MOID | 3.52162 AU (526.827 Gm) |
| Jupiter Tisserand parameter | 4.428 |
| Physical characteristics | |
| Dimensions | 1.3 km ~2–4 kmH |
| 2.6902 h (0.11209 d) | |
| 0.39 | |
| Temperature | ~250 K |
| S(I) (Gaffey) | |
| 16.0, 16.1 | |
| Discovery | |
|---|---|
| Discovery date | November 28, 2011 |
| Orbital characteristics | |
| Epoch December 09 2014 | |
| 2.1 km | |
| 0.7054 ± 0.0004 d | |
| Physical characteristics | |
| Dimensions | 0.46 km |
5261 Eureka is the first Mars trojan discovered. It was discovered by David H. Levy and Henry Holt at Palomar Observatory on June 20, 1990 from the Palomar Observatory. It trails Mars (at the L5 point) at a distance varying by only 0.3 AU during each revolution (with a secular trend superimposed, changing the distance from 1.5–1.8 AU around 1850 to 1.3–1.6 AU around 2400). Minimum distances from the Earth, Venus, and Jupiter, are 0.5, 0.8, and 3.5 AU, respectively.
Long-term numerical integration shows that the orbit is stable. Kimmo A. Innanen and Seppo Mikkola note that "contrary to intuition, there is clear empirical evidence for the stability of motion around the L4 and L5 points of all the terrestrial planets over a timeframe of several million years".
Since the discovery of 5261 Eureka, the Minor Planet Center has recognized three other asteroids as Martian trojans: 1999 UJ7 at the L4 point, 1998 VF31 at the L5 point, and 2007 NS2, also at the L5 point. At least five other asteroids in near-1:1 resonances with Mars have been discovered, but they do not exhibit trojan behavior. They are 2001 FR127, 2001 FG24, (36017) 1999 ND43, 1998 QH56 and (152704) 1998 SD4.
...
Wikipedia