 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[1] | |
| 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 | ~440AU (epoch 2000) |
| Eccentricity | 0.99978 |
| Orbital period | ~9,200 years (outbound) |
| Inclination | 138.78° |
| Last perihelion | 17 January 1910 |
| Physical characteristics[2] | |
Mean radius | 1.67 km (1.04 mi)[a] |
| Comet total magnitude (M1) | 5.2 |
| –5.0 (1910 apparition)[3] | |
TheGreat January Comet of 1910, formally designatedC/1910 A1 and often referred to as theDaylight Comet,[4] was acomet which appeared in January 1910. It was already visible to thenaked eye when it was first noticed, and many people independently "discovered" the comet. At its brightest, it outshone the planetVenus, and was possibly the brightest comet of the 20th century.[3]
The comet came tosolar conjunction about 1 degree from the Sun on 17 December 1909 but was still about 1 AU from the Sun. In January the comet brightened rather suddenly, and was initially visible from theSouthern Hemisphere only. A number of individuals claimed "discovery", but the comet is thought to have been first spotted by diamond miners in theTransvaal before dawn on January 12, 1910, by which time it was already a prominent naked-eye object ofapparent magnitude −1.0 with adeclination of −29 (i.e. best seen from the Southern Hemisphere).[3]
The first person to study the comet properly wasScottish astronomerRobert T. A. Innes at the Transvaal Observatory inJohannesburg on January 17, after having been alerted two days earlier by the editor of a Johannesburg newspaper.
The comet reachedperihelion on January 17 and was at that time visible in daylight with the unaided eye, having a magnitude of –5.0 due to theforward scattering of light.[3] It came to solar conjunction a second time on 18 January 1910.[5] Following perihelion, it declined in brightness but became a spectacular sight from theNorthern Hemisphere in the evening twilight, its noticeably curved tail reaching up to 50 degrees by early February.[3]
The year 1910 saw considerable media interest in the predicted return ofHalley's Comet, which reached perihelion on April 20. The appearance of the Daylight Comet several months earlier therefore came as something of a surprise, and made an extremely strong impression on an expectant public; when Halley's Comet returned again in1986, many older people's accounts of having seen it in 1910 clearly referred to the Daylight Comet instead.[6]
Owing to a "telephonic error", the comet was initially reported as being named Drake's Comet, though once the error was realised the press afterwards referred to it as the Daylight Comet or Sunset Comet, as no single individual was credited with its discovery.[7]
Newspapers in various cities reported people having been scared by the appearance of the comet.[8] The Morning Post ofCamden, New Jersey reported that similar scares happened in past years when comets had been seen.[9] InKorea many thought the comet would kill them all off. Some stopped going to work, just ate and drank and waited for the world to end.[10]
Outside politics the recently discovered daylight comet has been the chief topic of the week in England. It appears that the name of "Drake's comet", by which it has been generally known here, was given by mistake owing to a telephonic error, and it now goes by the name of the daylight or sunset comet.
.png)
