Saturday, February 5, 2011

Mapping the Universe- SDSS

Messier 51, The Whirlpool Galaxy. The SDSS image of this famous spiral galaxy (interacting with a smaller neighbor at the lower left) occupies about three one-millionths of the total sky area imaged by the SDSS. The SDSS imaging survey detected about 100 million galaxies, most of them much more distant, and thus much smaller and fainter in appearance, than M51. Some of these distant galaxies can be seen as small extended sources on this image, while the sharper, point-like sources are mostly foreground stars in our own Milky Way galaxy. The diameter of M51 is roughly 75,000 light years.
Credit: The Sloan Digital Sky Survey.

If you love looking at the starry night sky, then the Sloan Digital Sky Survey (SDSS) website is just where you need to go on those cloudy nights.

"The Sloan Digital Sky Survey (SDSS) is one of the most ambitious and influential surveys in the history of astronomy. Over eight years of operations (SDSS-I, 2000-2005; SDSS-II, 2005-2008), it obtained deep, multi-color images covering more than a quarter of the sky and created 3-dimensional maps containing more than 930,000 galaxies and more than 120,000 quasars. SDSS data have been released to the scientific community and the general public in annual increments, with the final public data release from SDSS-II scheduled for October 31, 2008. SDSS-III, a program of four new surveys using SDSS facilities, began observations in July 2008, and will continue through 2014.

The SDSS used a dedicated 2.5-meter telescope at Apache Point Observatory, New Mexico, equipped with two powerful special-purpose instruments. The 120-megapixel camera imaged 1.5 square degrees of sky at a time, about eight times the area of the full moon. A pair of spectrographs fed by optical fibers measured spectra of (and hence distances to) more than 600 galaxies and quasars in a single observation. A custom-designed set of software pipelines kept pace with the enormous data flow from the telescope."

Sloan Digital Sky Survey


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