Great Southern Comet of 1887
Encyclopedia
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.
A curious feature of the comet was the fact that few, if any observations were made of a cometary head or nucleus. As a result, some older astronomical texts refer to it as the "Headless Wonder".
at Córdoba, Argentina
, on January 19, at which point it was located in the constellation
Grus
. However, correspondence from William Henry Finlay
suggests that it may also have been seen from Blauwberg, South Africa
, on January 18. At the time of discovery the comet had already passed perihelion a week earlier, and its closest approach to Earth had been a month earlier.
, and was widely observed by astronomers in the Southern Hemisphere for the remainder of January. On the 22nd Finlay described it as a "pale narrow ribbon of light, quite straight" of about 35 degrees in length, though no cometary head could be distinguished. On the 23rd, Thome recorded a tail length of over 40 degrees, but like other observers stated he could not find a nucleus. On January 27, C. Todd recorded seeing the comet's head as a "diffused nebulous mass", but noted a break between the head and the tail (possibly representing what is referred to as a tail disconnection event).
Following the publication of an ephemeris
by S. C. Chandler
, which suggested the comet could be located 20° from Rigel
by the end of February, astronomers in the United States eagerly waited for it to move far enough into northern skies to be visible. However, the comet faded extremely rapidly, and never became visible from northern latitudes. It was last observed by John Tebbutt from New South Wales
on January 30, a relatively short period of observation overall for a large comet.
; however definitive calculation was difficult due to the fact that no observations were made of the nucleus. By February, Finlay had derived an orbit which linked the comet firmly to the Kreutz Sungrazing group. A more definitive orbit was calculated in 1978 by Zdeněk Sekanina, based on the assumption that the comet's head was on a great circle
"through the sun and inner part of the tail".
Sekanina was subsequently to speculate that the unusual appearance of the comet was due to a "tail formation event", an outburst of cometary dust, about 6 hours after perihelion. This event and the rapidly fading brightness, Sekanina argued, showed that C/1887 B1, along with C/1945 X1 (du Toit), represented a class of comets in between the "great" sungrazers (such as the Great Comet of 1882
) and the many smaller objects discovered by the Solar and Heliospheric Observatory
.
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
designation, was a bright comet
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...
seen from 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"...
during January 1887. Later calculations indicated it to be part of the Kreutz Sungrazing
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...
group.
A curious feature of the comet was the fact that few, if any observations were made of a cometary head or nucleus. As a result, some older astronomical texts refer to it as the "Headless Wonder".
Discovery
The comet was officially discovered by astronomer John Macon ThomeJohn M. Thome
John Macon Thome was an American-Argentine astronomer. Some sources say John Macom Thome. He is sometimes known as Juan M...
at Córdoba, Argentina
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 January 19, at which point it was located in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Grus
Grus (constellation)
Grus is a constellation in the southern sky. Its name is Latin for the crane, a species of bird. It was introduced in the late sixteenth century.-History:The stars that form Grus were originally considered part of Piscis Austrinus...
. However, correspondence from William Henry 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...
suggests that it may also have been seen from Blauwberg, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, on January 18. At the time of discovery the comet had already passed perihelion a week earlier, and its closest approach to Earth had been a month earlier.
Observations
The comet reached first magnitudeMagnitude (astronomy)
Magnitude is the logarithmic measure of the brightness of an object, in astronomy, measured in a specific wavelength or passband, usually in optical or near-infrared wavelengths.-Background:...
, and was widely observed by astronomers in the Southern Hemisphere for the remainder of January. On the 22nd Finlay described it as a "pale narrow ribbon of light, quite straight" of about 35 degrees in length, though no cometary head could be distinguished. On the 23rd, Thome recorded a tail length of over 40 degrees, but like other observers stated he could not find a nucleus. On January 27, C. Todd recorded seeing the comet's head as a "diffused nebulous mass", but noted a break between the head and the tail (possibly representing what is referred to as a tail disconnection event).
Following the publication of an ephemeris
Ephemeris
An ephemeris is a table of values that gives the positions of astronomical objects in the sky at a given time or times. Different kinds of ephemerides are used for astronomy and astrology...
by S. C. Chandler
Seth Carlo Chandler
Seth Carlo Chandler, Jr. was an American astronomer.He was born in Boston, Massachusetts. During his last year in high school he performed mathematical computations for Benjamin Peirce, of the Harvard College Observatory.After graduating, he became the assistant of Benjamin A. Gould...
, which suggested the comet could be located 20° from Rigel
Rigel
Rigel is the brightest star in the constellation Orion and the sixth brightest star in the sky, with visual magnitude 0.18...
by the end of February, astronomers in the United States eagerly waited for it to move far enough into northern skies to be visible. However, the comet faded extremely rapidly, and never became visible from northern latitudes. It was last observed by John Tebbutt from New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
on January 30, a relatively short period of observation overall for a large comet.
Analysis
The first, speculative, orbit was calculated by Heinrich KreutzHeinrich 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...
; however definitive calculation was difficult due to the fact that no observations were made of the nucleus. By February, Finlay had derived an orbit which linked the comet firmly to the Kreutz Sungrazing group. A more definitive orbit was calculated in 1978 by Zdeněk Sekanina, based on the assumption that the comet's head was on a great circle
Great circle
A great circle, also known as a Riemannian circle, of a sphere is the intersection of the sphere and a plane which passes through the center point of the sphere, as opposed to a general circle of a sphere where the plane is not required to pass through the center...
"through the sun and inner part of the tail".
Sekanina was subsequently to speculate that the unusual appearance of the comet was due to a "tail formation event", an outburst of cometary dust, about 6 hours after perihelion. This event and the rapidly fading brightness, Sekanina argued, showed that C/1887 B1, along with C/1945 X1 (du Toit), represented a class of comets in between the "great" sungrazers (such as the Great Comet of 1882
Great Comet of 1882
The Great Comet of 1882 formally designated C/1882 R1, 1882 II, and 1882b, was a comet which became very bright in September 1882...
) and the many smaller objects discovered by the Solar and Heliospheric Observatory
Solar and Heliospheric Observatory
The Solar and Heliospheric Observatory is a spacecraft built by a European industrial consortium led by Matra Marconi Space that was launched on a Lockheed Martin Atlas IIAS launch vehicle on December 2, 1995 to study the Sun, and has discovered over 2100 comets. It began normal operations in May...
.