2020 CD3
2020 CD3 (also 2020CD3 or CD3 for short) is a tiny near-Earth asteroid (or minimoon) that ordinarily orbits the Sun but makes close approaches to the Earth–Moon system, in which it can temporarily enter Earth orbit through temporary satellite capture (TSC). It was discovered at the Mount Lemmon Observatory by astronomers Theodore Pruyne and Kacper Wierzchoś on 15 February 2020, as part of the Mount Lemmon Survey or Catalina Sky Survey. The asteroid's discovery was announced by the Minor Planet Center on 25 February 2020, after subsequent observations confirmed that it was orbiting Earth.
2020 CD3 imaged in colour by Gemini North | |
| Discovery | |
|---|---|
| Discovered by | Mt. Lemmon Survey
|
| Discovery site | Mt. Lemmon Obs. (CSS) |
| Discovery date | 15 February 2020 |
| Designations | |
MPC designation | 2020 CD3 |
Alternative designations | C26FED2 |
Minor planet category | NEO · Arjuna · Apollo temporarily captured · co-orbital |
| Orbital characteristics | |
| Epoch 2022-Aug-09 (JD 2459800.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 2.03 yr (742 days) |
| Earliest precovery date | 9 May 2018 |
| Aphelion | 1.0418 AU |
| Perihelion | 1.0162 AU |
Semi-major axis | 1.029 AU |
| Eccentricity | 0.01245 (Geocentric hyperbolic e=58901) |
Orbital period (sidereal) | 1.04 yr (381.25 d) |
Mean anomaly | 151.09° |
Mean motion | 0° 56m 40.373s / day |
| Inclination | 0.63407° |
Longitude of ascending node | 82.211° |
| 49.972° | |
| Earth MOID | 0.0212 AU (3.17 million km; 8.3 LD) |
| Physical characteristics | |
Mean diameter | 0.9±0.1 m (albedo of 0.35) 1.2±0.1 m (albedo of 0.23) |
| Mass | ~4,900 kg (est.) |
Mean density | 2.1±0.7 g/cm3 |
Synodic rotation period | 1,146.8 s or 19.114 min (double-peaked solution) 573.4 s (single-peaked solution) |
| 0.35 (assumed V-type) 0.23 (assumed from main belt) | |
| V B–V=0.90±0.07 V–R=0.46±0.08 R–I=0.44±0.06 | |
| >30 (current) 20 (at discovery) | |
| 31.80±0.34 31.8 | |
It is the second temporary satellite of Earth discovered in situ, after 2006 RH120, which was discovered in 2006. Based on its nominal trajectory, 2020 CD3 was captured by Earth around 2016–2017, and escaped Earth's gravitational sphere of influence around 7 May 2020. 2020 CD3 will make another close pass to Earth in March 2044, though it will most likely not be captured by Earth due to the greater approach distance.
2020 CD3 has an absolute magnitude around 32, indicating that it is very small in size. Assuming that 2020 CD3 has a low albedo characteristic of dark, carbonaceous C-type asteroids, its diameter is probably around 1.9–3.5 metres (6–11 ft). 2020 CD3 is classified as an Arjuna asteroid, a subtype of small Earth-crossing Apollo asteroids that have Earth-like orbits.