The Great January Comet of 1910, formally designated C/1910 A1 and often referred to as the Daylight Comet,. was a

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...

which appeared in January 1910. It was already visible to the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying, light-collecting optical instrument, such as a telescope or microscope, or eye protection. Vision corrected to normal ...

when it was first noticed, and many people independently "discovered" the comet. At its brightest, it outshone the planet

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...

, and was possibly the brightest comet of the 20th century.

Discovery

The comet came to

solar conjunction Solar conjunction generally occurs when a planet or other Solar System object is on the opposite side of the Sun from the Earth. From an Earth reference, the Sun will pass between the Earth and the object. Communication with any spacecraft in sol ...

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 the Southern Hemisphere only. A number of individuals claimed "discovery", but the comet is thought to have been first spotted by diamond miners in the

Transvaal Transvaal is a historical geographic term associated with land north of (''i.e.'', beyond) the Vaal River in South Africa. A number of states and administrative divisions have carried the name Transvaal. * South African Republic (1856–1902; af, ...

before dawn on January 12, 1910, by which time it was already a prominent naked-eye object of

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

−1 with a

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the ...

of −29 (i.e. best seen from the Southern Hemisphere). The first person to study the comet properly was Scottish astronomer

Robert T. A. Innes Robert Thorburn Ayton Innes FRSE FRAS (10 November 1861 – 13 March 1933) was a Scottish astronomer best known for discovering Proxima Centauri in 1915, and numerous binary stars. He was also the first astronomer to have seen the Great January ...

at the Transvaal Observatory in

Johannesburg Johannesburg ( , , ; Zulu and xh, eGoli ), colloquially known as Jozi, Joburg, or "The City of Gold", is the largest city in South Africa, classified as a megacity, and is one of the 100 largest urban areas in the world. According to Demo ...

on January 17, after having been alerted two days earlier by the editor of a Johannesburg newspaper. The comet reached

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

on January 17 and was at that time visible in daylight with the unaided eye, having a magnitude of –5 due to the

forward scatter In physics, telecommunications, and astronomy, forward scatter is the deflection—by diffraction, nonhomogeneous refraction, or nonspecular reflection by particulate matter of dimensions that are large with respect to the wavelength in question ...

ing of light. It came to solar conjunction a second time on 18 January 1910. Following perihelion, it declined in brightness but became a spectacular sight from the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...

in the evening twilight, its noticeably curved tail reaching up to 50 degrees by early February.

Halley's Comet and the Daylight Comet

The year 1910 saw considerable media interest in the predicted return of

Halley's Comet Halley's Comet or Comet Halley, officially designated 1P/Halley, is a short-period comet visible from Earth every 75–79 years. Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and thus the o ...

, 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 in 1986, many older people's accounts of having seen it in 1910 clearly referred to the Daylight Comet instead.. 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.

Panic

Newspapers in various cities reported people having been scared by the appearance of the comet. The Morning Post of Camden, New Jersey reported that similar scares happened in past years when comets had been seen. In Korea 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.

References

External links

Donald Yeomans, "Great Comets in History". (Accessed 5/6/08)The Great Daylight Comet of 1910
by John W. Bortle, Sky and Telescope * {{DEFAULTSORT:1910 A1 Non-periodic comets

Great January Comet Of 1910 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 independent ...

19100112 Great comets

Discovery

Halley's Comet and the Daylight Comet

Panic

See also

References

External links