| Minorplanet: | yes |
| Background: |
|
| 203 Pompeja | |
| Pronounced: | [1] |
| Discoverer: | C. H. F. Peters |
| Discovered: | 25 September 1879 |
| Mpc Name: | (203) Pompeja |
| Alt Names: | A879 SA, 1895 EA |
| Named After: | Pompeii |
| Mp Category: | Main belt |
| Epoch: | 31 July 2016 (JD 2457600.5) |
| Semimajor: | 2.7367AU |
| Perihelion: | 2.5766AU |
| Aphelion: | 2.8968AU |
| Eccentricity: | 0.058490 |
| Inclination: | 3.1780° |
| Asc Node: | 347.916° |
| Arg Peri: | 57.060° |
| Mean Anomaly: | 47.6383° |
| Avg Speed: | 18.01 km/s |
| Mass: | (1.251 ± 0.640/0.401) kg |
| Density: | 1.626 ± 0.831/0.521 g/cm |
| Rotation: | 24.052abbr=onNaNabbr=on |
| Spectral Type: | DCX: |
| Abs Magnitude: | 8.97 |
| Mean Motion: | / day |
| Orbit Ref: | [2] |
| Uncertainty: | 0 |
203 Pompeja is a fairly large main-belt asteroid. It was discovered by C. H. F. Peters on September 25, 1879, in Clinton, New York, and named after Pompeii, the Roman town destroyed in volcanic eruption in AD 79. This asteroid is orbiting the Sun at a distance of with an eccentricity (ovalness) of 0.06 and a period of . The orbital plane is tilted at an angle of 3.2° to the plane of the ecliptic.[2]
Based upon photometric observations taken during 2011, it has a synodic rotation period of 24.052 ± 0.001 h, with a peak-to-peak amplitude of 0.10 ± 0.01 in magnitude. Because the rotation period nearly matches that of the Earth, it required coordinated observations from multiple observatories at widely spaced latitudes to produce a complete light curve. As discovered in 2021, the asteroid has a very red color due to tholins on its surface, similar to trans-Neptunian objects. It is therefore thought to have formed in the outer Solar System despite its current orbit within the asteroid belt.