Monday, December 26, 2011
THE DA VINCI GLOW
GUEST BLOG— Check the skies, TONIGHT for a spectacular conjunction in the Western sky between Venus and the slender crescent in the western sky, according to NASA.Gov’s Dr. Tony Phillips, who produces a first rate news page called Science@NASA.gov.
“…The action began Dec. 26 shortly before sunset. Around 4:30 pm to 5 pm local time, just as the sky is assuming its evening hue, Venus will pop into view, glistening bright in the deepening twilight. No more than 6 degrees to the right lies the crescent Moon, exquisitely slender, grinning like the Cheshire cat with his head cocked at humorous attention. This was a wonderful time to look; there were very few sights in the heavens as splendid as Venus and the Moon gathered close and surrounded by twilight blue.
"As the sky faded to black, a ghostly image of the full Moon materialized within the horns of the lunar crescent. This is caused by Earthshine, a delicate veil of sunlight reflected from our own blue planet onto the dusty-dark lunar terrain. Also known as "the Da Vinci glow," after Leonardo da Vinci who first understood it 500 years ago, Earthshine pushes the beauty of the conjunction over the top.
“Meanwhile, Jupiter will be looking down on it all from a perch overhead in the constellation Pisces. In ascending order, Jupiter, Venus and the Moon are the three brightest objects in the night sky, able to pierce city lights and even thin clouds. Almost everyone, everywhere will be able to see them.
“Although no telescope is required to enjoy the show, if one happens to be under your Christmas tree, take it outside. With a simple triangular sweep, you can see the clouds and moons of Jupiter, mountains and craters on the Moon, and the fat gibbous form of Venus. (Like the Moon, Venus has phases, and at the moment she is 83% illuminated.) Rarely can so much amateur astronomy be done with so little effort. Some people find the night after Christmas to be a bit of a letdown. This year, it's not so bad.” --By Dr. Tony Phillis, NASA.gov.
Images: A crescent moon with Earthshine over Yosemite National Park in October 2004. Photo credit: NASA.gov’s Andy Skinner.
Leonardo made this sketch of a crescent moon with Earthshine. It appears in the Codex Leicester circa 1510, where there is a page entitled "Of the Moon: No Solid Body is Lighter than Air." He explains the "ghostly glow" is due to sunlight bouncing off Earth's oceans and, in turn, hitting the Moon. Not bad for an earthling, who lived when most folks were still believing the earth was still flat.