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Astronomy Picture of the Day 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. 2002 July 8 Weighing Empty Space Credit & Copyright: Bell Labs-Lucent Technologies, AURA, NOAO, NSF Explanation: Sometimes staring into empty space is useful. Pictured above is a region of sky that was picked because it had, well, nothing: no bright stars, no bright galaxies, and no picturesque nebulas. What could not be avoided, however, were a few stars in our own Galaxy, and many distant galaxies strewn across...

Astronomy Picture of the Day 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. 2002 June 29 A Deep Field In The Southern Sky Credit: R. Williams (STScI), HDF-S Team, NASA Explanation: This deep view of the cosmos is the sequel to the 1995 hit Hubble Space Telescope Deep Field. Billed as the Hubble Deep Field South, it was produced by pointing the space telescope toward a patch of sky in the southern constellation Tucana. Over a period of 10 days, many...

Astronomy Picture of the Day 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. 2002 June 5 NGC 3621: Far Beyond the Local Group Credit: F. Bresolin, R.-P. Kudritzki, R. Mendez (Institute for Astronomy, Univ. Hawaii) Explanation: Far beyond the local group of galaxies lies NGC 3621, some 22 million light-years away. Found in the serpentine southern constellation Hydra, the loose spiral arms of this gorgeous island universe are loaded with luminous young star clusters and dark dust lanes. Still, for earthbound...

Astronomy Picture of the Day 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. 2002 May 29 Cosmic Ripples Implicate Dark Universe Credit: Very Small Array Collaboration Explanation: What may appear fuzzy to some makes things crystal clear to others. The cosmic microwave background radiation emanating from the universe could only have the above fuzzy pattern if it contained clear amounts of dark matter and dark energy. The conclusion, based on a detailed analysis of the temperature and spacing of the bumps,...

Astronomy Picture of the Day 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. 2002 April 5 Gamma-Ray Burst Afterglow: Supernova Connection Credit: HST Image: D.W. Fox, J.S. Bloom, S.R. Kulkarni (Caltech), et al. XMM Result: J.N. Reeves, D. Watson, J.P. Osborne (University of Leicester), et al. Explanation: What causes the mysterious gamma-ray bursts? Indicated in this Hubble Space Telescope exposure of an otherwise unremarkable field in the constellation Crater, is the dwindling optical afterglow of a gamma-ray burst first detected by...

Astronomy Picture of the Day 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. 2002 April 3 NGC 4414: A Flocculent Spiral Galaxy Credit: Olivier Vallejo (Observatoire de Bordeaux), HST, ESA, NASA Explanation: How much mass do flocculent spirals hide? The above true color image of flocculent spiral galaxy NGC 4414 was taken with the Hubble Space Telescope to help answer this question. Flocculent spirals -- galaxies without well defined spiral arms -- are a quite common form of galaxy, and NGC...

Astronomy Picture of the Day 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. 2002 March 31 The Mysterious Rings of Supernova 1987A Credit: (ESA/ STScI), HST, NASA Explanation: What's causing those odd rings in supernova 1987A? In 1987, the brightest supernova in recent history occurred in the Large Magellanic Clouds. At the center of the picture is an object central to the remains of the violent stellar explosion. When the Hubble Space Telescope was pointed at the supernova remnant in 1994,...

Astronomy Picture of the Day 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. 2002 March 19 Breaking Distant Light Credit: VIMOS, VLT, ESO Explanation: In the distant universe, time appears to run slow. Since time-dilated light appears shifted toward the red end of the spectrum (redshifted), astronomers are able to use cosmological time-slowing to help measure vast distances in the universe. Above, the light from distant galaxies has been broken up into its constituent colors (spectra), allowing astronomers to measure the...