2021 PH27
| Discovery | |
|---|---|
| Discovered by | S. S. Sheppard |
| Discovery site | Cerro Tololo Obs. |
| Discovery date | 13 August 2021 |
| Designations | |
| 2021 PH27 | |
| v13aug1 | |
| Atira · NEO | |
| Orbital characteristics | |
| Epoch 2025 May 05 (JD 2460800.5) | |
| Uncertainty parameter 2 | |
| Observation arc | 6.63 yr (2,421 days) |
| Earliest precovery date | 16 July 2017 |
| Aphelion | 0.7903 AU |
| Perihelion | 0.1331 AU |
| 0.4617 AU | |
| Eccentricity | 0.7116 |
| 0.31 yr (114.60 days) | |
| 140.26° | |
| 3° 8m 28.02s / day | |
| Inclination | 31.941° |
| 39.396° | |
| 7 October 2021 @ 106 km/s | |
| 8.579° | |
| Earth MOID | 0.2254 AU |
| Mercury MOID | 0.1123 AU |
| Venus MOID | 0.0147 AU |
| Physical characteristics | |
| >1 km | |
| 19.3 (discovery) 14 (unobservable) | |
| 17.69±0.235 | |
2021 PH27 is a near-Earth asteroid of the Atira group. It was discovered by Scott Sheppard using the Dark Energy Survey's DECam imager at NOIRLab's Cerro Tololo Inter-American Observatory on 13 August 2021. 2021 PH27 has the smallest semi-major axis and shortest orbital period among all known asteroids as of 2021, with a velocity at perihelion of 106 km/s (240,000 mph). It also has the largest relativistic perihelion shift of any object orbiting the Sun, 1.6 times that of Mercury. With an absolute magnitude of 17.7, the asteroid is estimated to be larger than 1 kilometer (0.6 miles) in diameter.