lovejoy

As seen from the European Very Large Telescope.

Via NASA:

What causes the structure in Comet Lovejoy's tail? Comet C/2014 Q2 (Lovejoy), which is currently at naked-eye brightness and near its brightest, has been showing an exquisitely detailed ion tail. As the name implies, the ion tail is made of ionized gas -- gas energized by ultraviolet light from the Sun and pushed outward by the solar wind. The solar wind is quite structured and sculpted by the Sun's complex and ever changing magnetic field. The effect of the variable solar wind combined with different gas jets venting from the comet's nucleus accounts for the tail's complex structure. Following the wind, structure in Comet Lovejoy's tail can be seen to move outward from the Sun even alter its wavy appearance over time. The blue color of the ion tail is dominated by recombining carbon monoxide molecules, while the green color of the coma surrounding the head of the comet is created mostly by a slight amount of recombiningdiatomic carbon molecules.

Via PRI:

Comet Lovejoy, a bright celestial ball of dust and ice probably born in the Oort Cloud, is currently traveling across the skies of the Northern Hemisphere. While photographer Gerald Rhemann snagged a shot of Lovejoy on December 22 (from the Southern Hemisphere), casual observers in the top half of the world might be able to enjoy the show into February.

"Comets this bright [appear only] every few years, on average," says Matthew Knight, a research scientist who studies comets at Lowell Observatory in Flagstaff, Arizona. Indeed, some viewers with keen sight might be able to spy it with the naked eye from a location far from urban lights— think the Arizona desert or Michigan's Upper Peninsula.