ヘール・ボップ彗星
The Great Comet of 1811, formally designated C/1811 F1, is a comet that was visible to the naked eye for around 260 days, the longest recorded period of visibility until the appearance of Comet Hale–Bopp in 1997. In October 1811, at its brightest, and when it was 1.2 AU from Earth, it displayed an apparent magnitude of 0, with an easily visible coma.