Despite orbital calculations showing that it had a period of several centuries, some astronomers wondered if it was a return of the 1680 comet. A bright comet seen in 1880 was found to be travelling on an almost identical orbit to that of 1843, as was the subsequent Great Comet of 1882. Some astronomers suggested that perhaps they were all one comet, whose orbital period was somehow being drastically shortened at each perihelion passage, perhaps by retardation by some dense material surrounding the Sun. An alternative suggestion was that the comets were all fragments of an earlier Sun-grazing comet. This idea was first proposed in 1880, and its plausibility was amply demonstrated when the Great Comet of 1882 broke up into several fragments after its perihelion passage. In 1888, Heinrich Kreutz published a paper showing that the comets of 1843 (C/1843 D1, the Great March Comet), 1880 (C/1880 C1, the Great Southern Comet), and 1882 (C/1882 R1, Great September Comet) were probably fragments of a giant comet that had broken up several orbits before. The comet of 1680 proved to be unrelated to this family of comets. After another Kreutz sungrazer was seen in 1887 (C/1887 B1, the Great Southern Comet of 1887), the next one did not appear until 1945. Two further sungrazers appeared in the 1960s, Comet Pereyra in 1963 and Comet Ikeya–Seki, which became extremely bright in 1965, and broke into three pieces after its perihelion. The appearance of two Kreutz Sungrazers in quick succession inspired further study of the dynamics of the group. The group generally has an Inclination of roughly 140 degrees, a perihelion distance of around 0.01 AU, and a Longitude of ascending node of 340–10°. Notable members The brightest members of the Kreutz sungrazers have been spectacular, easily visible in the daytime sky. The three most impressive have been the Great Comet of 1843, the Great Comet of 1882 and X/1106 C1. The progenitor of all Kreutz sungrazers observed to date may be the Great Comet of 371 BC, or comets seen in 214 BC, 423 AD or 467 AD. Another notable Kreutz sungrazer was the Eclipse Comet of 1882 (see further below). Great Comet of 371 BC The Great Comet seen in the winter of 372–371 BC was an extremely bright comet thought to be the progenitor of the entire Kreutz sungrazer family. It was observed by Aristotle and Ephorus during the