25. COMET HALE-BOPP

It is not true that comets are always coming from the Kuiperbelt or the Oortcloud. There is a wellknown comet not of that origine and which is "long-periodic": Comet Hale-Bopp. A comet with a very long-stretched elliptical orbit in a plane perpendicular to the plane of the planets and with a period of 4200 years. Its "perihelion" (closest position near the sun and the reversal point) is 138 million km, so nearer to the sun than to the earth. He passed the earth on 200 million km on 23 March 1997, leading to a very impressive appearance on the firmament during the years 1995-1998. According to the measurements he will never touch the earth. The comet has a diameter 40 km, being a very rough estimate.