3753 Cruithne
3753 Cruithne is a Q-type, Aten asteroid in orbit around the Sun in 1:1 orbital resonance with Earth, making it a co-orbital object. It is an asteroid that, relative to Earth, orbits the Sun in a bean-shaped orbit that effectively describes a horseshoe, and that can change into a quasi-satellite orbit. Cruithne does not orbit Earth and at times it is on the other side of the Sun, placing Cruithne well outside of Earth's Hill sphere. Its orbit takes it near the orbit of Mercury and outside the orbit of Mars. Cruithne orbits the Sun in about one Earth year, but it takes 770 years for the series to complete a horseshoe-shaped movement around Earth.
| Discovery | |
|---|---|
| Discovered by | Duncan Waldron |
| Discovery date | 10 October 1986 |
| Designations | |
MPC designation | (3753) Cruithne |
| Pronunciation | English: /kruˈiːnjə/ kroo-EEN-yə Irish: [ˈkɾˠɪ(h)nʲə, ˈkɾˠʊnʲə] |
Named after | Cruthin |
Alternative designations | 1983 UH; 1986 TO |
Minor planet category | |
| Orbital characteristics | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 16087 days (44.04 yr) |
| Aphelion | 1.5114 AU (226,100,000 km) |
| Perihelion | 0.48405 AU (72,413,000 km) |
Semi-major axis | 0.99774 AU (149,260,000 km) |
| Eccentricity | 0.51485 (213000 wrt Earth) |
Orbital period (sidereal) | 1.00 yr (364.02 d) |
Average orbital speed | 27.73 km/s |
Mean anomaly | 257.46° |
Mean motion | 0° 59m 20.436s / day |
| Inclination | 19.805° |
Longitude of ascending node | 126.23° |
| 43.831° | |
| Earth MOID | 0.07119 AU (10,650,000 km) |
| Physical characteristics | |
Mean diameter | ~5 km |
| Mass | 1.3×1014 kg |
Synodic rotation period | 27.30990 h (1.137913 d) |
| 0.15 | |
| Q | |
| 15.6 | |
The name Cruithne is from Irish and refers to the early Picts (Old Irish: Cruthin) in the Annals of Ulster and their eponymous king ("Cruidne, son of Cinge") in the Pictish Chronicle.