"COSMIC BLUES: This week, bright Comet Lovejoy (C/2014 Q2) is passing by the Pleiades, creating a photogenic conjunction for astrophotographers. The sinuous tail of the comet is on the very doorstep of the Seven Sisters. Alan Dyer, author of "How to Shoot Nightscapes and Timelapses," took this picture on Jan. 18th from a remote corner of New Mexico: "Lovejoy's long blue ion tail stretched back well past the Pleiades, a distance of at least 12°," says Dyer. "I shot this image from the dark skies of The City of Rocks State Park, New Mexico, which has proven to be one of the finest places on the planet for watching the comet!"
Many observers have noted the similar colors of the Pleiades and the comet's tail. Both are a beautiful shade of cosmic blue. Despite their similar appearance, however, the two blues come from different physics. The comet's tail is blue because it contains ionized carbon monoxide (CO+), a gas which fluoresces blue in the near-vacuum of interplanetary space. The nebulosity surrounding the Pleiades is blue because grains of interstellar dust embedded in the gas scatter the blue light of hot young stars at the cluster's core." PHOTO: "Comet Lovejoy & Pleiades" by Alan Dyer, on www.Spaceweather.com http://amazingsky.photoshelter.com/