C/2017 U7 (PanSTARRS)
C/2017 U7 (PanSTARRS) is a hyperbolic comet (previously classified as A/2017 U7, a hyperbolic asteroid), first observed on 29 October 2017 by astronomers of the Pan-STARRS facility at Haleakala Observatory, Hawaii, United States when the object was 7.8 AU (1.2 billion km) from the Sun. Despite being discovered only 10 days after interstellar asteroid 1I/'Oumuamua, it was not announced until March 2018 (along with C/2018 C2 (Lemmon), which was believed to be another hyperbolic asteroid at the time) as its orbit is not strongly hyperbolic beyond most Oort Cloud comets. Based on the absolute magnitude of 10.6, it may measure tens of kilometers in diameter. As of August 2018, there is only 1 hyperbolic asteroid known, ʻOumuamua, but hundreds of hyperbolic comets are known.
Trajectory through solar system | |
| Discovery | |
|---|---|
| Discovered by | Pan-STARRS |
| Discovery site | Haleakala Obs. |
| Discovery date | 29 October 2017 |
| Designations | |
MPC designation | C/2017 U7 |
Alternative designations | P10EwQh, A/2017 U7 |
Minor planet category | hyperbolic comet |
| Orbital characteristics | |
| Epoch 29 November 2017 (JD 2458086.5) | |
| Uncertainty parameter n.a. | |
| Observation arc | 176 days |
| Earliest precovery date | 18 August 2017 |
| Perihelion | 6.4187±0.0008 AU |
Semi-major axis | −3700±300 AU |
| Eccentricity | 1.0018±0.0001 1.000008 (Barycentric epoch 2200) |
Orbital period (sidereal) | ~800000 years (inbound barycentric epoch 2000) |
Mean anomaly | n.a. |
Mean motion | 0° 0m 0.016s / day |
| Inclination | 142.6390° |
Longitude of ascending node | 276.217° |
| 325.95° | |
| Earth MOID | 5.468 AU |
| Jupiter MOID | 1.635 AU |
| Physical characteristics | |
| Dimensions | 13.5–59 km (assumed) |
| 20.6 (March 2018) | |
| 10.6±0.62 | |