Astronomy Picture of the Day
APOD: 2005 September 4 - Comet Hale Bopp Over Val Parola Pass
Explanation: Comet Hale-Bopp became much brighter than any surrounding stars. It was seen even over bright city lights. Out away from city lights, however, it put on quite a spectacular show. Here Comet Hale-Bopp was photographed above Val Parola Pass in the Dolomite mountains surrounding Cortina d'Ampezzo, Italy. Comet Hale-Bopp's blue ion tail was created when fast moving particles from the solar wind struck expelled ions from the comet's nucleus. The white dust tail is composed of larger particles of dust and ice expelled by the nucleus that orbit behind the comet. Observations showed that Comet Hale-Bopp's nucleus spins about once every 12 hours.
APOD: 2005 May 22 - The Dust and Ion Tails of Comet Hale-Bopp
Explanation: In 1997, Comet Hale-Bopp's intrinsic brightness exceeded any comet since 1811. Since it peaked on the other side of the Earth's orbit, however, the comet appeared only brighter than any comet in two decades. Visible above are the two tails shed by Comet Hale-Bopp. The blue ion tail is composed of ionized gas molecules, of which carbon monoxide particularly glows blue when reacquiring electrons. This tail is created by the particles from the fast solar wind interacting with gas from the comet's head. The blue ion tail points directly away from the Sun. The light colored dust tail is created by bits of grit that have come off the comet's nucleus and are being pushed away by the pressure of light from the Sun. This tail points nearly away from the Sun. The above photograph was taken in March 1997.
APOD: 2004 October 3 - Comet Hale Bopp and the North America Nebula
Explanation: Comet Hale-Bopp's 1997 encounter with the inner Solar System allowed many breath-taking pictures. Above, Comet Hale-Bopp was photographed crossing the constellation of Cygnus, sporting spectacular yellow dust and blue ion tails. Visible on the right in red is the North America Nebula, a bright emission nebula observable from a dark location with binoculars. The North America Nebula is about 1500 light-years away, much farther than the comet, which was only about 8 light minutes away. Several bright blue stars from the open cluster M39 are visible just above the comet's blue ion tail.
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NASA Official: Jay Norris. Specific rights apply.
A service of: EUD at NASA / GSFC
& Michigan Tech. U.