Great January Comet of 1910
C/1910 A1, the Daylight or Great January Comet, photograph from Lowell Observatory | |
| Discovery | |
|---|---|
| Discovery date | 12 January 1910 |
| Designations | |
| 1910 I, 1910a | |
| Orbital characteristics | |
| Epoch | 9 January 1910 (JD 2418680.5) |
| Observation arc | 82 days |
| Number of observations | 25 |
| Aphelion | ~1150 AU (inbound) ~900 AU (outbound) |
| Perihelion | 0.12896 AU (19.292 million km) |
| Semi-major axis | ~440 AU (epoch 2000) |
| Eccentricity | 0.99978 |
| Orbital period | ~9,200 years (outbound) |
| Inclination | 138.78° |
| Last perihelion | 17 January 1910 |
| Physical characteristics | |
Mean radius | 1.67 km (1.04 mi) |
| Comet total magnitude (M1) | 5.2 |
| –5.0 (1910 apparition) | |
The Great January Comet of 1910, formally designated C/1910 A1 and often referred to as the Daylight Comet, was a comet which appeared in January 1910. It was already visible to the naked eye when it was first noticed, and many people independently "discovered" the comet. At its brightest, it outshone the planet Venus, and was possibly the brightest comet of the 20th century.