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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. 2003 March 3 Will the Universe End in a Big Rip? Illustration Credit & Copyright: Lynette Cook Explanation: How will our universe end? Recent speculation now includes a pervasive growing field of mysterious repulsive energy that rips virtually everything apart. Although the universe started with a Big Bang, analysis of recent cosmological measurements allows a possibility that it will end with a Big Rip. As soon as few...

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. 2003 February 9 COBE Dipole: Speeding Through the Universe Credit: DMR, COBE, NASA, Four-Year Sky Map Explanation: Our Earth is not at rest. The Earth moves around the Sun. The Sun orbits the center of the Milky Way Galaxy. The Milky Way Galaxy orbits in the Local Group of Galaxies. The Local Group falls toward the Virgo Cluster of Galaxies. But these speeds are less than the speed...

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. 2003 January 24 Seyfert's Sextet Credit: J. English (U. Manitoba), C. Palma (PSU), et al., NASA Explanation: Known as Seyfert's Sextet, this intriguing group of galaxies lies in the head portion of the split constellation Serpens. The sextet actually contains only four interacting galaxies, though. Near the center of this Hubble Space Telescope picture, the small face-on spiral galaxy lies in the distant background and appears only 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. 2003 January 8 Abell 1689 Warps Space Credit: N. Benitez (JHU), T. Broadhurst (Hebrew Univ.), H. Ford (JHU), M. Clampin(STScI), G. Hartig (STScI), G. Illingworth (UCO/Lick), ACS Science Team, ESA, NASA Explanation: Two billion light-years away, galaxy cluster Abell 1689 is one of the most massive objects in the Universe. In this view from the Hubble Space Telescope's Advanced Camera for Surveys, Abell 1689 is seen to warp...

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 October 12 Chandra Deep Field Credit: Riccardo Giacconi et al., JHU, AUI, NASA Explanation: Officially the Chandra Deep Field - South, this picture represents the deepest ever x-ray image of the Universe. One million seconds of accumulated exposure time with the orbiting Chandra X-ray Observatory went in to its making. Concentrating on a single, otherwise unremarkable patch of sky in the constellation Fornax, this x-ray image corresponds...

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 19 Counting Stars in the Infrared Sky Credit: J. Carpenter, M. Skrutskie, R. Hurt, 2MASS Project, NSF, NASA Explanation: The bulging center of our Milky Way Galaxy, dark cosmic clouds, the thin galactic plane, and even nearby galaxies are easy to spot in this sky view. But each pixel in the digital image is actually based on star counts alone -- as derived from the Two...

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 11 M51: X-Rays from the Whirlpool Credit: A. Wilson (UMD) et al., CXC, NASA Explanation: Fresh from yesterday's episode, a popular pair of interacting galaxies known as the Whirlpool debut here beyond the realm of visible light -- imaged at high energies by the orbiting Chandra X-ray Observatory. Still turning in a remarkable performance, over 80 glitering x-ray stars are present in the Chandra image data...

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 10 M51: Cosmic Whirlpool Credit & Copyright: Tony and Daphne Hallas Explanation: Follow the handle of the Big Dipper away from the dipper's bowl, until you get to the handle's last bright star. Then, just slide your telescope a little south and west and you'll likely find this stunning pair of interacting galaxies, the 51st entry in Charles Messier's famous catalog. Perhaps the original spiral nebula,...

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 May 6 NGC 4676: When Mice Collide Credit: ACS Science & Engineering Team, NASA Explanation: These two galaxies are pulling each other apart. Known as "The Mice" because they have such long tails, each spiral galaxy has likely already passed through the other and will probably collide again and again until they coalesce. The long tails are created by the relative difference between gravitational pulls on the...

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 9 A Quasar Portrait Gallery Credit J. Bahcall (IAS, Princeton), M. Disney (Univ. Wales), NASA Explanation: Quasars (QUASi-stellAR objects) lie near the edge of the observable Universe. Discovered in 1963, astronomers were astounded that such objects could be visible across billions of light-years, as this implies they must emit prodigious amounts of energy. Where does the energy come from? Many believe the quasar's central engine is...

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 11 The 100-Meter Green Bank Radio Telescope Credit: NRAO, NSF Explanation: The largest single-dish fully steerable radio telescope began operation in 2000 August in Green Bank, West Virginia, USA. Dedicated as the Robert C. Byrd Green Bank Telescope, the device weighs over 30 times more than the Statue of Liberty, and yet can point anywhere in the sky more precisely than one thousandth of a degree....