

Comet Ison passing by Earth - onion2k
http://www.nasa.gov/content/goddard/timeline-of-comet-ison-s-dangerous-journey/#.UoyAH2TBsmU

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DavidWanjiru
Do they mean to say that it's never completed a single orbit around the sun
since the solar system was formed? Is it possible for an orbit around the sun
to be that huge? I mean, just because we only observed it for the first time
in 2012 doesn't mean it's never been to this part of th solar system before,
or does it? I wouldn't know, but I'm struggling with the notion that there is
a body that is in orbit around the sun that is yet to complete an orbit since
the solar system was formed all those billions of years ago.

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onion2k
Ison was likely just hanging about in the Oort cloud until a the tidal impulse
of passing galaxy nudged it enough for it to "fall" towards the sun. To get
here it's travelled at least 100,000 AU (9.3 trillion miles), and not
especially quickly at that. I _think_ is the first time it's gone past because
it's actually very new in comet terms.

