Great Comet of 1843

C/1843 D1

A painting of the sungrazing Great Comet of 1843, as seen from Tasmania, by Mary Morton Allport
Discovery
Discovery date	February 5, 1843
Alternative designations	Great Comet of 1843, Great March Comet, 1843 I, 1843 D1
Orbital characteristics A
Epoch	2394259.411
Aphelion	156 AU
Perihelion	.005460 AU
Semi-major axis	78 AU
Eccentricity	0.99993
Orbital period	742? yr
Inclination	144.4°
Last perihelion	February 27, 1843
Next perihelion	unknown

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 is also known as the Great March Comet). 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 (X/1106 C1) 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.

First observed in early February, 1843, it raced toward an incredibly close perihelion of less than 830,000 km on February 27, 1843; at this time it was observed in broad daylight roughly a degree away from the Sun. It passed closest to Earth on March 6, 1843, and was at its greatest brilliance the following day; unfortunately for observers north of the equator, at its peak it was best visible from the Southern Hemisphere. It was last observed on April 19, 1843. At that time this comet had passed closer to the Sun than any other known object.

The Great Comet of 1843 developed an extremely long tail during and after its perihelion passage. At over two astronomical units in length, it was the longest known cometary tail until measurements in 1996 showed that Comet Hyakutake's tail was almost twice as long. There is a painting in the National Maritime Museum that was created by astronomer Charles Piazzi Smyth. The purpose of the painting is to show the overall brightness and size of the tail of the comet.