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The last time Comet West came around was about 550,000 BC, very roughly the time of: the last reversal of Earth's magnetic field, about 750,000 BC; and the appearance of Homo Sapiens on Earth, about 200,000 BC, as determined by autosomal and mitochondrial DNA studies and Y-chromosome studies. (see Hammer, M., Nature 378 (23 Nov 1995) 376) The 1976 appearance of Comet West was about the 6th time it had returned since the beginning of our current Ice Age about 3,000,000 years ago, and about the 120th time it had returned since the great comet collision with the Earth that resulted in the extinction of the dinosaurs about 65,000,000 years ago, and about the 500th time it had returned since the end of the preceding Ice Age about 250,000,000 years ago, the time of the Permian-Triassic extinction in which the number of species of marine life on Earth was reduced by over 90 per cent and about the 8,000th time it had returned since the Earth was formed about 4.4 billion years ago and bombarded by a swarm of comets.
According to a Cometography web page by Gary Kronk: "... Comet C/2002 C1 Ikeya-Zhang ... was discovered ... on 2002 February 1. ... This graphic
was created by Larry Koehn and shows the motion through the inner solar system during March and April. ...".
According to a web article by John E. Bortle in Sky and Telescope: "... Comet Ikeya-Zhang (C/2002 C1) ...
... brightness peaked near 3rd magnitude in early April. ... by late April, the comet has definitely faded; observers now report that its tail has shrunk and its magnitude has dropped to between 4.5 and 5.0. ... Within days of the discovery, astronomers noticed similarities between the orbital path of Ikeya-Zhang and that of other comets observed in 1532 and 1661. Calculations now strongly suggest this is the object seen in 1661, which is making its first return visit to the inner solar system in 341 years. No other comet with such a long period has been witnessed on successive orbits around the Sun. ....".
According to an 8 April 2002 web article by Paul Deans in Sky and Telescope: "... Comet Ikeya-Zhang and the Andromeda Galaxy (M31) make a pretty pair in this image
acquired on April 4th. Although not visually obvious, the comet sports a (blue) gas tail as well as a dust tail. ...".
According to the Comet Observation Home Page of Charles Morris at JPL:
"... Image ...[from]... "G. V. Schiaparelli Astronomical Observatory" Varese Italy ... Andrea Aletti & Luca Buzzi ...
... of Comet C/2001 RX14 and NGC 3726 on December 14 . This has got to be one of the most interesting comet images ever taken. ...".
Acccording to a 19 February 2003 BBC web article: "... The comet ... C/2002 V1 ... returns after 37,000 years ...[when the Geminga shock wave hit the Earth, Cro-Magnons appeared, and the Rule of Gods on Earth began. The comet]... is unusual in that it is very large
and very bright. ... it is the brightest comet ever observed by one of Soho's instruments. ...". According to a SOHO web page: "... Although comet NEAT (C/2002 V1) was not visible in the LASCO images until about 16:00 (Universal Time) on February 16, it had in fact been tracked by SOHO since December 31 last year. ... The LASCO pictures and movies of this comet are quite out of the ordinary ...[a Gary W. Kronk's Cometography web page states "... the perihelion date was firmly established as February 18.30, the perihelion distance was given as 0.0993 AU, and the orbital period was about 37 thousand years. The orbit indicates the comet passed closest to Earth on December 24 (0.80 AU) and will be situated 5.7° from the sun around the time of perihelion ...". That page also has this "... collage
of four images obtained by the Solar & Heliospheric Observatory (SOHO) at 10:54 UT on 2003 February 17, 18, 19, and 20. ..."]...
with a sizeable tail and a very bright (saturated) comet nucleus. We even got a nice Coronal Mass Ejection (CME) off the west limb close to perihelion time ...".
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