Comet Hale–Bopp - Wikipedia, the free encyclopedia

Comet Hale–Bopp - Wikipedia, the free encyclopedia:

 "The comet may have been observed by ancient Egyptians during the reign of pharaoh Pepi I (2332–2283 BC). In Pepi's pyramid in Saqqara is a text referring to an "nhh-star" as a companion of the pharaoh in the heavens, where "nhh" is the hieroglyph for long hair.[10]"

"The estimated probability of impacting Earth in future passages through the inner Solar System is remote, about 2.5 x 10⁻⁹ per orbit.^[33] However, given that the comet nucleus is around 60 km in diameter,^[1] the consequences of such an impact would be apocalyptic. A calculation given by Weissman^[33] conservatively estimates the diameter at 35 km; an estimated density of 0.6 g/cm³ then gives a cometary mass of 1.3 x 10¹⁹ g. An impact velocity of 52.5 km/s yields an impact energy of 1.9 x 10³² ergs, or 4.4 x 10⁹ megatons, about 44 times the estimated energy of the K-T impact event."

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