Halley's Comet is the only known short-period comet that is consistently visible to the naked eye from Earth, appearing every 72–80 years, though with the majority of recorded apparations occurring after 75–77 years. It last appeared in the inner parts of the Solar System in 1986 and will next appear in mid-2061. Officially designated 1P/Halley, it is also commonly called Comet Halley, or sometimes simply Halley.
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. It was a member of the Kreutz Sungrazers, a family of comets resulting from the breakup of a parent comet into multiple fragments in about 1106. These comets pass extremely close to the surface of the Sun—within a few solar radii—and often become very bright as a result.
The Great Comet of 1882, formally designated as C/1882 R1, 1882 II, and 1882b, was a comet which became very bright in September 1882. It was a member of the Kreutz Sungrazers, a family of comets which pass within 1 R☉ of the Sun's photosphere at perihelion.
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.
Comet Skjellerup–Maristany, formally designated C/1927 X1, 1927 IX, and 1927k, was a long-period comet which became very bright in 1927. This great comet was observable to the naked eye for about 32 days. It was independently discovered by amateur astronomers John Francis Skjellerup in Australia on 28 November 1927 and Edmundo Maristany in Argentina on 6 December 1927, and noted for its strong yellow appearance and the detection of emission from sodium atoms.
C/1680 V1, also called the Great Comet of 1680, Kirch's Comet, and Newton's Comet, was the first comet discovered by telescope. It was discovered by Gottfried Kirch and was one of the brightest comets of the seventeenth century.
Comet McNaught, also known as the Great Comet of 2007 and given the designation C/2006 P1, is a non-periodic comet discovered on 7 August 2006 by British-Australian astronomer Robert H. McNaught using the Uppsala Southern Schmidt Telescope. It was the brightest comet in over 40 years, and was easily visible to the naked eye for observers in the Southern Hemisphere in January and February 2007.
The Great Comet of 1577 is a non-periodic comet that passed close to Earth with first observation being possible in Peru on 1 November 1577. Final observation was made on 26 January 1578.
The Great Comet of 1264 was one of the brightest comets on record. It appeared in July 1264 and remained visible to the end of September.
The Great Comet of 1556 was a comet that first appeared in February 1556, and which was observed throughout much of Europe. The comet appears to have been seen in some places before the end of February, but it was not generally observed until the middle of the first week in March. Its apparent diameter was equal to half that of the Moon, and the tail was said to resemble "the flame of a torch agitated by the wind." Cornelius Gemma said that the head of the comet, when it first appeared, was as large as Jupiter, and that its color resembled that of Mars.
The Great Comet of 1901, sometimes known as Comet Viscara, formally designated C/1901 G1, was a comet which became bright in the spring of 1901. Visible exclusively from the southern hemisphere, it was discovered on the morning of April 12, 1901 as a naked-eye object of second magnitude with a short tail. On the day of perihelion passage, the comet's head was reported as deep yellowish in color, trailing a 10-degree tail. It was last seen by the naked eye on May 23.
C/2011 L4 (PanSTARRS), also known as Comet PANSTARRS, is a non-periodic comet discovered in June 2011 that became visible to the naked eye when it was near perihelion in March 2013. It was discovered using the Pan-STARRS telescope located near the summit of Haleakalā, on the island of Maui in Hawaii. Comet C/2011 L4 probably took millions of years to come from the Oort cloud. After leaving the planetary region of the Solar System, the post-perihelion orbital period is estimated to be roughly 107000 years. Dust and gas production suggests the comet nucleus is roughly 1 kilometer (0.62 mi) in diameter, while based on the absolute nuclear magnitude and a geometric albedo of 0.04 the diameter of the nucleus is over 2.4 kilometers (1.5 mi). A method based on coma magnitude decay function estimated the effective radius at 2.317 ± 0.190 km.
A great comet is a comet that becomes exceptionally bright. There is no official definition; often the term is attached to comets such as Halley's Comet, which during certain appearances are bright enough to be noticed by casual observers who are not looking for them, and become well known outside the astronomical community. Typically, they are as bright or brighter than a second magnitude star and have tails that are 10 degrees or longer under dark skies. Great comets appear at irregular, unpredictable intervals, on average about once per decade. Although comets are officially named after their discoverers, great comets are sometimes also referred to by the year in which they appeared great, using the formulation "The Great Comet of ...", followed by the year. It can also be used as a generic name when a very bright comet is discovered by many observers simultaneously.
C/1874 H1 (Coggia) is a non-periodic comet, which in the summer of 1874 could be seen by the naked eye. On the basis of its brightness, the comet has been called the Great Comet of 1874; on July 13 of that year its apparent magnitude peaked at between 0 and 1.
C/1807 R1, also known as the Great Comet of 1807, is a long-period comet. It was visible to naked-eye observers in the northern hemisphere from early September 1807 to late December, and is ranked among the great comets due to its exceptional brightness.
C/1769 P1 (Messier) is a long-period comet that was visible to the naked eye at its last apparition in 1769. The comet is classified as a great comet due to its superlative brightness.
The Great Comet of 1819, officially designated as C/1819 N1, also known as Comet Tralles, was an exceptionally bright and easily visible comet, approaching an apparent magnitude of 1–2, discovered July 1, 1819 by the German astronomer Johann Georg Tralles in Berlin. It was the first comet analyzed using polarimetry, by French mathematician François Arago.
The Great Comet of 1472 was visible from Christmas Day 1471 to 1 March 1472, for a total of 59 days. The comet passed 0.07 AU from Earth on 22 January 1472, closer than any other great comet in modern times.
C/1618 W1 is a comet that was visible to the naked eye in 1618 and 1619. It is classified as a "Great Comet" due to its extraordinary brightness and its long tail, measuring up to 90° long.
The Southern Comet of 1947 was a bright comet that became visible in the southern hemisphere in December 1947. At that point, it was the brightest comet seen in two decades and is one of the brightest comets seen since 1935, with an estimated maximum apparent magnitude of -3.
