Daylight comet

Also visible during the day: Comet C / 1858 L1 (Donati) , painting by William Dyce: Pegwell Bay, Kent - a Recollection of October 5th 1858

As daylight comet some of the brightest are comets called who were even during the day to see the blue sky. In particular, these are the following large comets :

• C / -43 K1 (Comet Caesar) , 44 BC - Sidus Iulium, Caesaris astrum, Caesar's daylight comet
• C / 1843 D1 (Great March Comet) - daylight comet from 1843
• C / 1910 A1 (Great January Comet) - daylight comet from 1910
• C / 1927 X1 (Skjellerup-Maristany) - rarely also: daylight comet from 1927

The name is based on the fact that before the development of the international nomenclature (named after the discoverer) important comets were simply given popular names in public. The name itself goes back in particular to the comet of 1910, which became known as "The Great Daylight Comet".

In order to be clearly visible in the daytime sky , at least a magnitude of about −4 to −5 is necessary (maximum brightness of Venus). Comet C / 1965 S1 (Ikeya-Seki) even reached −10 mag (almost the brightness of the full moon) in the immediate vicinity of the Sun, but sank to −4 mag during the following 20 hours. Even the comet McNaught was visible during the day freiäugig in January 2007 on good sites.

Telescopic daytime observations are possible when the comet's head is brighter than a first magnitude star . If it appears almost point-like and is at a greater distance from the sun, a brightness of 2 to 3 may be sufficient.

See also

• Visibility of comets
• Day observation
• Surface brightness

Individual evidence

1. ↑ so Chemisches Zentralblatt 1939, p. 2555 ( limited preview in the Google book search).
2. ↑ Comet Info, The Top 10 Comets
3. ↑ K.Wurm: The comets . Understandable Science Volume 53, Springer 1954