Discover the cosmos! Each day a different image or photograph of
our fascinating universe is featured, along with a brief
explanation written by a professional astronomer. 2007 December
31 Explanation: Two spectacular comets graced Earth's skies
during 2007. Both comets became bright enough to be seen by the
unaided eye of the casual sky enthusiast. Early in 2007, Comet
McNaught grew brighter than any comet in 40 years, displaying a
beautiful dust tail that flowed across the sky. Comet McNaught
(c/2006 P1) became known as the Great Comet of 2007, sported
unusual striations in its expansive dust tail, and showed
unexpectedly complex chemistry in its ion tail. Toward the
year's end, normally docile and faint Comet Holmes brightened
suddenly and unexpectedly to naked eye visibility. Remarkably,
Comet 17P/Holmes stayed bright for weeks even though it lies
beyond the orbit of Mars. No distant comet in recent history has
remained so bright for so long. In this view, a white Comet
Holmes was photographed in early De