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Astronomy Picture Of the Day (APOD)
Cosmic Rays from Galactic Centers
12.11.2007
Where do cosmic rays come from? A major step toward answering this century old question may have just come in from the Auger Observatory project, the world's premier cosmic ray observatory. That high energy fundamental particles are barreling through the universe has been known for about a century.
NGC 6888: The Crescent Nebula
11.11.2007
What caused the Crescent Nebula? Looking like an emerging space cocoon, the Crescent Nebula, visible in the center of the above image, was created by the brightest star in its center. A leading progenitor hypothesis has the Crescent Nebula beginning to form about 250,000 years ago.
A Tale of Comet Holmes
10.11.2007
A beautiful blue ion tail has become visible in deep telescopic images of Comet Holmes. Pointing generally away from the Sun and also planet Earth, the comet's ion tail is seriously foreshortened by our extreme viewing angle.
Skyscape with Comet Holmes
9.11.2007
This gorgeous skyscape spans some 10 degrees across the heroic constellation Perseus, about the size of a generous binocular field of view. The deep exposure includes bright stars, emission nebulae, star clusters, and, of course, the famous Comet Holmes. To identify the celestial landmarks, just place your cursor over the image.
VERITAS and Venus
8.11.2007
Early morning risers and late to bed astronomers have recently enjoyed bright planets in predawn skies, with brilliant Venus above the eastern horizon. On November 5, Venus was joined by the waning crescent Moon.
The Sloan Great Wall: Largest Known Structure
7.11.2007
What is the largest structure known? The answer might depend on how one defines "structure." A grouping of galaxies known as the Sloan Great Wall was discovered in the Sloan Digital Sky Survey and is a leading candidate.
An X Class Flare Region on the Sun
6.11.2007
Why does the Sun flare? Unpredictably, our Sun unleashes tremendous flares expelling hot gas into the Solar System that can affect satellites, astronauts, and power grids on Earth. This close up of an active region on the Sun that produced a powerful X-class flare was captured by the orbiting TRACE satellite.
Comet Holmes Grows a Tail
5.11.2007
Comet Holmes continues to be an impressive sight to the unaided eye. The comet has diminished in brightness only slightly, and now clearly appears to have a larger angular extent than stars and planets. Astrophotographers have also noted a distinctly green appearance to the comet's coma over the past week.
The Closest Galaxy: Canis Major Dwarf
4.11.2007
What is the closest galaxy to the Milky Way? The new answer to this old question is the Canis Major dwarf galaxy. For many years astronomers thought the Large Magellan Cloud (LMC) was closest, but its title was supplanted in 1994 by the Sagittarius dwarf galaxy.
Golden Comet Holmes
3.11.2007
Surprising Comet Holmes remains easily visible as a round, fuzzy cloud in the northern constellation Perseus. Skywatchers with telescopes, binoculars, or those that just decide to look up can enjoy the solar system's latest prodigy as it glides about 150 million kilometers from Earth, beyond the orbit of Mars.
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