2020 VT4
2020 VT4 is a tiny near-Earth asteroid that passed 370 km (230 mi) above Earth's surface on 13 November 2020 at 17:20 UTC. The asteroid was discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey at the Mauna Loa Observatory fifteen hours after its closest approach to Earth. The Earth encounter perturbed the asteroid's trajectory from an Earth-crossing Apollo-type orbit to an Aten-type orbit, subsequently reducing the asteroid's heliocentric orbital period from 1.5 years to 0.86 years.
| Discovery | |
|---|---|
| Discovered by | ATLAS-MLO |
| Discovery site | Mauna Loa Obs. |
| Discovery date | 14 November 2020 |
| Designations | |
MPC designation | 2020 VT4 |
Alternative designations | A10sHcN |
Minor planet category | NEO · Apollo (pre-flyby) Aten (post-flyby) |
| Orbital characteristics | |
| Epoch 17 December 2020 (JD 2459200.5) (post-flyby as pre-flyby was very different) | |
| Uncertainty parameter 5 | |
| Observation arc | 5 days |
| Aphelion | 1.092 AU |
| Perihelion | 0.724 AU |
Semi-major axis | 0.908 AU |
| Eccentricity | 0.20299 |
Orbital period (sidereal) | 0.86 yr (315.92 d) |
Mean anomaly | 143.860° |
Mean motion | 1° 8m 22.286s / day |
| Inclination | 10.173° |
Longitude of ascending node | 231.422° |
| 14 November 2020 12:17 UT (pre-flyby) | |
| 53.678° | |
| Earth MOID | 0.0002 AU |
| Physical characteristics | |
Mean diameter | 5–11 m (assumed) |
| 20.0 (current) 17.3 (at discovery) | |
| 28.66±0.50 28.7 | |
2020 VT4 passed closer to Earth than any known asteroid, except for those that became meteors. It passed closer than 2020 QG and 2011 CQ1, which passed about 3,000 km and 5,500 km from Earth's surface, respectively. Given an estimated absolute magnitude of 28.7, 2020 VT4 is estimated to be around 5 to 10 metres in diameter. Had it impacted Earth, it would mostly have disintegrated during atmospheric entry and might have left a common strewn field.