Great Comet of 1882
Encyclopedia
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
which became very bright in September 1882. It was a member of the Kreutz Sungrazers
Kreutz Sungrazers
The Kreutz Sungrazers are a family of sungrazing comets, characterized by orbits taking them extremely close to the Sun at perihelion. They are believed to be fragments of one large comet that broke up several centuries ago and are named for German astronomer Heinrich Kreutz, who first...
, a family of comets which pass within 1 R☉ of the Sun's
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
photosphere
Photosphere
The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to the fact that it is a spheric surface perceived...
at perihelion.
The comet was bright enough to be visible next to the sun in the daytime sky at its perihelion.
Discovery
The comet appeared suddenly in the morning skies of September 1882, and as it was already visible to the naked eyeNaked eye
The naked eye is a figure of speech referring to human visual perception unaided by a magnifying or light-collecting optical device, such as a telescope or microscope. Vision corrected to normal acuity using corrective lenses is considered "naked"...
when it became visible it was discovered independently by many people. Reports suggest that it was first seen as early as 1 September 1882, from the Cape of Good Hope
Cape of Good Hope
The Cape of Good Hope is a rocky headland on the Atlantic coast of the Cape Peninsula, South Africa.There is a misconception that the Cape of Good Hope is the southern tip of Africa, because it was once believed to be the dividing point between the Atlantic and Indian Oceans. In fact, the...
as well as the Gulf of Guinea
Gulf of Guinea
The Gulf of Guinea is the northeasternmost part of the tropical Atlantic Ocean between Cape Lopez in Gabon, north and west to Cape Palmas in Liberia. The intersection of the Equator and Prime Meridian is in the gulf....
, and over the next few days many observers in the southern hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
reported the new comet.
The first astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
to record observations of the comet was W. H. Finlay
William Henry Finlay
William Henry Finlay was a South African astronomer. He was First Assistant at the Cape Observatory from 1873 to 1898. He discovered the periodic comet 15P/Finlay...
, the Chief Assistant at the Royal Observatory in Cape Town
Cape Town
Cape Town is the second-most populous city in South Africa, and the provincial capital and primate city of the Western Cape. As the seat of the National Parliament, it is also the legislative capital of the country. It forms part of the City of Cape Town metropolitan municipality...
, South Africa. Finlay's observation on 7 September at 16h GMT was also an independent discovery, and he reported that the comet had an apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of about 3, and a tail about a degree
Degree (angle)
A degree , usually denoted by ° , is a measurement of plane angle, representing 1⁄360 of a full rotation; one degree is equivalent to π/180 radians...
in length.
The comet brightened rapidly, and within days had become an exceptionally bright object. Her Majesty's Astronomer at the Cape, David Gill
David Gill (astronomer)
Sir David Gill FRS was a Scottish astronomer who is known for measuring astronomical distances, for astrophotography, and for geodesy. He spent much of his career in South Africa.- Life and work :...
, reported watching the comet rise a few minutes before the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
on 18 September, and described it as "The nucleus was then undoubtedly single, and certainly rather under than over 4″ in diameter; in fact, as I have described it, it resembled very much a star of the 1st magnitude seen by daylight. ".
Perihelion
The comet was rapidly approaching perihelion when it was discovered.At perihelion, the comet is estimated to have been only 300,000 miles from the sun's surface.
Subsequent orbital studies have determined that it was a Sungrazing comet
Sungrazing comet
A sungrazing comet is a comet that passes extremely close to the Sun at perihelion – sometimes within a few thousand kilometres of the Sun's surface. While small sungrazers can be completely evaporated during such a close approach to the Sun, larger sungrazers can survive many perihelion passages...
, one which passes extremely close to the surface of the Sun.
For many hours on either side of its perihelion passage, the comet was easily visible in the daytime sky next to the Sun.
It reached an estimated magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of −17.
Shortly after perihelion was reached on 17 September, the comet transited
Astronomical transit
The term transit or astronomical transit has three meanings in astronomy:* A transit is the astronomical event that occurs when one celestial body appears to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point...
the Sun.
At the Cape, Finlay observed the comet with the aid of a neutral density filter
Neutral density filter
In photography and optics, a neutral density filter or ND filter can be a colorless or grey filter. An ideal neutral density filter reduces and/or modifies intensity of all wavelengths or colors of light equally, giving no changes in hue of color rendition.The purpose of standard photographic...
right up until the moment of transit, when the Sun's limb was "boiling all about it".
Finlay noted that the comet disappeared from view very suddenly, and no trace of it could be seen against the Sun's surface.
Post-perihelion evolution
After its perihelion passage, the comet moved into dark skies, and although it faded as it receded from the Sun it remained one of the most prominent objects in the sky. On 30 September, observers, including Finlay and E. E. Barnard, began to notice that the comet's nucleus was elongated and broken into two pronounced bright balls of light, and by 17 October it was clear that it had broken into at least five fragments. Observers reported that the relative brightness of the fragments varied from day to day.In mid-October, the comet developed a notable antitail
Antitail
An Antitail is a term used in astronomy to describe one of the three tails, all pointing in different directions, which may appear to emanate from a comet as it passes close to the Sun. The antitail appears, when viewed from Earth, as a spike projecting from the comet's coma towards the sun, and...
, pointing towards the Sun. Anti-tails are a fairly common cometary phenomenon, and result from orbital geometry giving the appearance of a tail pointing towards the Sun although material can only be driven away from the Sun.
The nucleus reached its maximum apparent size in December 1882. The comet faded gradually, but despite its fragmentation it remained visible to the naked eye until February 1883. The last definite sighting of the comet was made by B. A. Gould at Córdoba
Córdoba, Argentina
Córdoba is a city located near the geographical center of Argentina, in the foothills of the Sierras Chicas on the Suquía River, about northwest of Buenos Aires. It is the capital of Córdoba Province. Córdoba is the second-largest city in Argentina after the federal capital Buenos Aires, with...
on 1 June 1883.
Orbital studies
Studies of the orbit of the comet showed that the Great Comet of 1882 was moving on an almost identical path to previous great cometGreat comet
A Great Comet is a comet that becomes exceptionally bright. There is no official definition; often the term will be attached to comets that become bright enough to be noticed by casual observers who are not actively looking for them, and become well known outside the astronomical community. Great...
s seen in C/1843 D1
Great Comet of 1843
The Great Comet of 1843 formally designated C/1843 D1 and 1843 I, was a long-period comet which became very bright in March 1843 . It was discovered on February 5, 1843 and rapidly brightened to become a great comet...
and C/1880 C1. These comets had also suddenly appeared in the morning sky and had passed extremely close to the Sun at perihelion. One suggestion was that all three were in fact the same comet, with an orbital period that was being drastically shortened at each perihelion passage. However, studies showed this to be untenable, as the orbital period of this comet is 772 ± 3 years and the others are 600–800 years.
Heinrich Kreutz
Heinrich Kreutz
Heinrich Carl Friedrich Kreutz was a German astronomer, most notable for his studies of the orbits of several sungrazing comets, which revealed that they were all related objects, produced when a very large sun-grazing comet fragmented several hundred years previously...
studied the orbits of the three great comets, and developed the idea that the three comets were fragments of a much larger progenitor comet which had broken up at an earlier perihelion passage. The fragmentation of the Great Comet of 1882 itself demonstrated that this was plausible. It is now thought that the Great Comet of 1882 is a fragment of X/1106 C1
X/1106 C1
X/1106 C1, also known as the Great Comet of 1106, was a Great Comet that appeared on February 2, 1106, and was observed across the world from the beginning of February through to mid-March. It was recorded by astronomers in Wales, England, Japan, Korea, China and Europe. It was observed to split...
, and that Comet du Toit (C/1945 X1) and Comet Ikeya-Seki
Comet Ikeya-Seki
Comet Ikeya–Seki, formally designated C/1965 S1, 1965 VIII, and 1965f, was a long-period comet discovered independently by Kaoru Ikeya and Tsutomu Seki...
(C/1965 S1) are two of its sister fragments.
It is now well established that the comets C/1843 D1
Great Comet of 1843
The Great Comet of 1843 formally designated C/1843 D1 and 1843 I, was a long-period comet which became very bright in March 1843 . It was discovered on February 5, 1843 and rapidly brightened to become a great comet...
, C/1880 C1, C/1882 R1, C/1887 B1
Great Southern Comet of 1887
The Great Southern Comet of 1887, or C/1887 B1 using its International Astronomical Union designation, was a bright comet seen from the Southern Hemisphere during January 1887. Later calculations indicated it to be part of the Kreutz Sungrazing group....
, C/1963 R1, C/1965 S1, and C/1970 K1 are all members of a family known as the Kreutz Sungrazers
Kreutz Sungrazers
The Kreutz Sungrazers are a family of sungrazing comets, characterized by orbits taking them extremely close to the Sun at perihelion. They are believed to be fragments of one large comet that broke up several centuries ago and are named for German astronomer Heinrich Kreutz, who first...
, which are all descended from one comet. Current models do not support the frequent supposition in the prior literature that the famous comet of 372 BC is in fact the ultimate parent of the Sungrazers. The comet of 372 BC is often associated with Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
who, along with others from his time, described that comet in his writings. However, Aristotle was only twelve at the time of the comet's appearance and the historian, Callisthenes of Olynthus, who also wrote about it was born ten years after its appearance. Consequently, their reports should not be taken as eye-witness accounts. Further, there is no mention of the comet in Chinese literature of the time. Instead either the comet of February 423 or of February 467 with orbital periods of around 700 years is now considered the likely progenitor of the Sungrazers. The fragments of the Great Comet of 1882 will return in several hundred years time, spread out over perhaps two or three centuries.