2015 SO2
| Discovery | |
|---|---|
| Discovered by | Črni Vrh Obs. | 
| Discovery date | 21 September 2015 | 
| Designations | |
| 2015 SO2 | |
| Orbital characteristics | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 1 | |
| Observation arc | 342 days | 
| Aphelion | 1.10688036 AU (165.586945 Gm) | 
| Perihelion | 0.890962 AU (133.2860 Gm) | 
| 0.99892124 AU (149.436491 Gm) | |
| Eccentricity | 0.108076 | 
| 1.00 yr (364.66602 d) | |
| 208.3767° | |
| 0° 59m 13.937s / day | |
| Inclination | 9.1750° | 
| 182.9293° | |
| 290.0678° | |
| Earth MOID | 0.0191611 AU (2.86646 Gm) | 
| Physical characteristics | |
| 50–111 m[a] | |
| 23.9 | |
2015 SO2 (astronomical naming convention: 2015 SO2) is an Aten asteroid that is a temporary horseshoe companion to the Earth, the ninth known Earth horseshoe librator. Prior to its most recent close encounter with our planet (2015 September 30) it was an Apollo asteroid.