Comet Hale–Bopp is a long-period comet that was one of the most widely observed of the 20th century and one of the brightest seen for many decades.
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 occuring 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.
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. First observed as a faint telescopic object on September 18, 1965, the first calculations of its orbit suggested that on October 21, it would pass just 450,000 km (280,000 mi) above the Sun's surface, and would probably become extremely bright.
12P/Pons–Brooks is a periodic comet with an orbital period of 71 years. Comets with an orbital period of 20–200 years are referred to as Halley-type comets. It is one of the brightest known periodic comets, reaching an absolute visual magnitude of about 5 in its approach to perihelion. Comet Pons-Brooks was conclusively discovered at Marseilles Observatory in July 1812 by Jean-Louis Pons, and on its next appearance in 1883 by William Robert Brooks. There are ancient records of comets that are suspected of having been apparitions of 12P/Pons–Brooks.
Comet West, formally designated C/1975 V1, 1976 VI, and 1975n, was a comet described as one of the brightest objects to pass through the inner Solar System in 1976. It is often described as a "great comet."
The Great Comet of 1882 formally designated 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 comet was bright enough to be visible next to the Sun in the daytime sky at its perihelion. The comet made its closest approach to Earth on 16 September 1882 at 0.99 AU and then came to perihelion the next day on 17 September.
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.
The Eclipse Comet of 1948, formally known as C/1948 V1, was an especially bright comet discovered during a solar eclipse on November 1, 1948. Although there have been several comets that have been seen during solar eclipses, the Eclipse Comet of 1948 is perhaps the best-known; it was however, best viewed only from the Southern Hemisphere.
Comet Pojmański is a non-periodic comet discovered by Grzegorz Pojmański on January 2, 2006, and formally designated C/2006 A1. Pojmański discovered the comet at Warsaw University Astronomic Observatory using the Las Campanas Observatory in Chile as part of the All Sky Automated Survey (ASAS). Kazimieras Cernis at the Institute of Theoretical Physics and Astronomy at Vilnius, Lithuania, located it the same night and before the announcement of Pojmański's discovery, in ultraviolet images taken a few days earlier by the SWAN instrument aboard the SOHO satellite. A pre-discovery picture was later found from December 29, 2005.
The Comet of 1729, also known as C/1729 P1 or Comet Sarabat, was an assumed parabolic comet with an absolute magnitude of −3, the brightest ever observed for a comet; it is therefore considered to be potentially the largest comet ever seen. With an assumed eccentricity of 1, it is unknown if this comet will return in a hundred thousand years or be ejected from the Solar System.
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 Southern Comet of 1887, or C/1887 B1 using its International Astronomical Union (IAU) 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. It came to perihelion on 11 January 1877 at a distance of 0.00483 AU (723 thousand km) with a velocity of 606.1 km/s. Since the Sun has a radius of 696000 km, the comet passed about 27000 km from the surface of the Sun.
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.
Comet Lovejoy, formally designated C/2011 W3 (Lovejoy), is a long-period comet and Kreutz sungrazer. It was discovered in November 2011 by Australian amateur astronomer Terry Lovejoy. The comet's perihelion took it through the Sun's corona on 16 December 2011, after which it emerged intact, though greatly impacted by the event.
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.
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/1865 B1 was a non-periodic comet, which in 1865 was so bright that it was visible to unaided-eye observations in the Southern Hemisphere. The comet could not be seen from the Northern Hemisphere.
C/2021 A1 (Leonard) was a long period comet that was discovered by G. J. Leonard at the Mount Lemmon Observatory on 3 January 2021 when the comet was 5 AU (750 million km) from the Sun. It had a retrograde orbit. The nucleus was about 1 km across. It came within 4 million km (2.5 million mi) of Venus, the closest-known cometary approach to Venus.
C/2023 A3 (Tsuchinshan–ATLAS) is a comet from the Oort cloud discovered by the Purple Mountain Observatory in China on 9 January 2023 and independently found by ATLAS South Africa on 22 February 2023. The comet passed perihelion at a distance of 0.39 AU on 27 September 2024, when it became visible to the naked eye. Tsuchinshan-ATLAS peaked its brightest magnitude shortly after passing the Sun at 9 October, with a magnitude of −4.9 per reported observations at the Comet Observation Database (COBS).
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.
