On Nov 17th, Comet ISON will conjunct with Spica in Virgo.  Depending on how you look at it, Virgo will give birth to comet ISON on 11/17.

At the SAME time, comet LINEAR will be in the constellation Bootes, conjuncting with Arcturus.  http://philologos.org/__eb-tws/chap11.htm#bootes  http://www.aerith.net/comet/catalog/2012X1/2012X1.html

Also note that comet LINEAR just exploded in the constellation of Coma.  http://spaceweather.com/  http://philologos.org/__eb-tws/chap11.htm#coma almost exactly 6 years to the day Comet 17P Holmes exploded in Perseus.

At the SAME time, comet Encke will be hanging out in Virgo, being 'born' out of Virgo on 11/10.

Interesting birthpang and constellation symbolism going on!