comet

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.

History was made Wednesday when the European Space Agency successfully landed a spacecraft on a comet for the first time ever.

"We're are on the comet!" #cometlanding https://t.co/c6xIWJp0TR

— ESA (@esa) November 12, 2014

Via NASA:

The Rosetta Mission lander is safely on a comet. One of Philae's feet appears at the bottom left of this spectacular image of the surface of C67/P Churyumov-Gerasimenko. Still a happy lander, Philae bounced twice before settling and returning images from the surface, traveling a kilometer or so after initially touching at the targeted site Agilkia. A surface panorama suggests that the lander has come to rest tilted and near a shadowing wall, with its solar panels getting less illumination that hoped. Philae's science instruments are working as planned and data is being relayed during communications windows, when the Rosetta spacecraft is above the lander's new horizon.

Esa's Rosetta mission is currently making its way towards a comet in the solar system. And, in a series of stunning new images, it reveals how comet 67P/Churyumov-Gerasimenko has begun to develop into an exciting ball of dust and gas. Over a period of six weeks the comet has begun to extend its dusty veil known as a 'coma' into space.

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.

Comet Ikeya-Seki,long-period comet that is one of a group of Sun-grazing comets having similar orbits and including the great comet known as 1882 II. Comet Ikeya-Seki was discovered Sept. 18, 1965, by two Japanese amateur astronomers, Ikeya Kaoru and Seki Tsutomu. Moving in a retrograde orbit, the comet made its closest approach to the Sun on Oct. 21, 1965, at a distance less than a solar radius from the surface.