Great Comet of 1402

Lore & Background

The most extensive account comes from Jacobus Angelus in Tractatus de Cometis, who reported the comet first seen in early February. By mid-March, the tail was about 45 degrees long, shaped like an inverted pyramid that became diffuse. Angelus last saw the comet on 26 or 27 March, noting 'three long and very thick hairs' (striae) in the east before sunrise, and another after sunset possibly the ion tail. The Italian Annales Forolivienses from 1473 places the comet east of Aries in late February and early March, growing brighter, and visible in daylight preceding the Sun by mid-March. The Korean text T'aejong Sillok records the comet first noticed on 20 February as a broom star with a tail 5–6° long in the area of Khuei (parts of Andromeda and Pisces); two days later the tail was 10 degrees long. It was last seen on 19 March. The comet is also mentioned in Russian, Muslim, and Japanese sources, but not by the Chinese. The historian Doukas, in Historia Byzantina (1462), describes a bright comet during the Battle of Ankara in July 1402, visible in daytime until the autumnal equinox, but no other source confirms this, and David Seargent suggests Doukas may have misdated the 1402 comet.

Reader's Guide

John Russell Hind calculated an approximate orbit in 1877 with a perihelion distance of 0.38 AU and a closest approach to Earth on 20 February at 0.71 AU. Olof Hiorter suggested in 1746 that the Great Comet of 1402 was a previous apparition of the Great Comet of 1744, based on appearance and roughly similar orbits, also linking comets of 1058 and 715; Heinrich Wilhelm Matthias Olbers and Johann Holetschek agreed. Maik Meyer and Gary Kronk calculated an orbit based on the 1744 comet, yielding an eccentricity of 0.995580 and an orbital period of 354 years; excluding daylight observations gave about 480 years. Integrating backward, they found a previous perihelion around 1405, and comparing with chronicle reports of the Great Comet of 1405 showed agreement in location and appearance, with an estimated perihelion on 25 March. They also identified candidate comets in 1032, 676, and 336 AD, and a possible link to Caesar's Comet in 44 BC. However, they noted observation reports contradict and considered the identification with the Great Comet of 1744 unlikely.

Did You Know?

• The comet was visible in daylight for eight days, the longest recorded for any comet.
• Jacobus Angelus described the tail as 45 degrees long and shaped like an inverted pyramid.
• The Korean text T'aejong Sillok recorded the comet's tail growing from 5–6° to 10° in two days.
• Meyer and Kronk found candidate comets in 1032, 676, and 336 AD as possible earlier apparitions.