| Discovery[1] | |
|---|---|
| Discovered by | Mount Lemmon Survey |
| Discovery date | 11 October 2021 |
| Designations | |
| 2021 TP21 | |
|
| |
| Orbital characteristics[2] | |
| Epoch 2021-Jul-01 (JD 2459396.5) | |
| Uncertainty parameter6 | |
| Observation arc | 57 days |
| Aphelion | 4.2274 AU (Q) |
| Perihelion | 0.81425 AU (q) |
| 2.5208 AU (a) | |
| Eccentricity | 0.67699 (e) |
| 4.00 years | |
| 318.4° (M) | |
| Inclination | 25.404° (i) |
| 8.089° (Ω) | |
| 116.3° (ω) | |
| Earth MOID | 0.03 AU (4.5 million km) |
| Jupiter MOID | 1.7 AU (250 million km) |
| Physical characteristics | |
| Dimensions |
|
| 20.2[2][4] | |
2021 TP21 is an Apophis-sized asteroid that was discovered on 11 October 2021 when it was 0.5 AU (75 million km) from Earth.[1] This potentially hazardous asteroid (PHA) spends most or its orbit closer to 4 AU (600 million km) from the Sun as objects orbit more slowly when near aphelion (furthest distance from the Sun). 2021 TP21 was rated with a Torino scale of 1 from 31 October 2021 to 4 November 2021 for a potential impact on 27 March 2081.[3] As the observation arc became longer the nominal distance from Earth became further on the potential impact date.
| Observation arc (in days) |
JPL Horizons nominal geocentric distance (AU) |
uncertainty region (3-sigma) |
Impact probability (1 in) |
Torino scale |
|---|---|---|---|---|
| 17 | 0.17 AU (25 million km)[5] | ± 1.5 billionkm[5] | 100000 | 0 |
| 19 | 1.4 AU (210 million km)[6] | ± 870 million km[6] | 50000[3] | 1[3] |
| 57 | 2.5 AU (370 million km)[7] | ± 18 million km[7] | 0 | 0 |
