| P/2003 T12 (SOHO) | |
| Discoverer: | SOHO |
| Discovery Date: | 10 October 2003 |
| Designations: | P/2003 T12 P/2012 A3 |
| Observation Arc: | 4,592 days (12.57 years) |
| Obs: | 491 |
| Epoch: | 25 May 2012 (JD 2456072.5) |
| Semimajor: | 2.568 AU |
| Eccentricity: | 0.77617 |
| Aphelion: | 4.5612 AU |
| Perihelion: | 0.5748 AU |
| Period: | 4.1153 years |
| Inclination: | 11.4752° |
| Asc Node: | 176.466° |
| Arg Peri: | 217.669° |
| Tjup: | 2.894 |
| Earth Moid: | 0.1547 AU |
| Jupiter Moid: | 1.0191 AU |
| M1: | 19.6 |
| Magnitude: | 8.5 (2012 apparition) |
| Last P: | 3 July 2024 |
| Next P: | 2028 |
P/2003 T12 is a periodic comet that revolves around the Sun once every 4.11 years. On January 13, 2012, it was observed by the satellite STEREO-B, and the most documented phase of P/2003 T12 was observed on that date. It is theorized to be a possible fragment of comet 169P/NEAT.
During its apparition on January 12, 2012, it ventured into the highest phase angle ever observed for a comet, and the forward-scattering enhancement in brightness was marked, as large as ~8.5 mag. This has given insight into Henyey-Greenstein (HG) space-dust.