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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 August 24 Valles Marineris: The Grand Canyon of Mars Credit: Viking Project, Explanation: The largest canyon in the Solar System cuts a wide swath across the face of Mars. Named Valles Marineris, the grand valley extends over 3,000 kilometers long, spans as much as 600 kilometers across, and delves as much as 8 kilometers deep. By comparison, the Earth's Grand Canyon in Arizona, USA is 800 kilometers...

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 26 Anticrepuscular Rays Over Horseshoe Canyon Credit & Copyright: Peggy Peterson Explanation: What's happening over the horizon? Although the scene may appear somehow supernatural, nothing more unusual is occurring than a setting Sun and some well placed clouds. Pictured above are anticrepuscular rays. To understand them, start by picturing common crepuscular rays that are seen any time that sunlight pours though scattered clouds. Now although sunlight...

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 18 Candor and Ophir Chasmata Credit: Viking Project, NASA Explanation: First imaged by the Mariner 9 spacecraft, Valles Marineris, the grand canyon of Mars, is a system of enormous depressions called chasmata that stretch some 4,000 kilometers along the Martian equator. Looking north over the canyon's central regions, Candor chasma lies in the foreground of this spectacular view with the steep walls of Ophir chasma near...

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 August 27 Valles Marineris: The Grand Canyon of Mars Credit: Viking Project, USGS, NASA Explanation: The largest canyon in the Solar System cuts a wide swath across the face of Mars. Named Valles Marineris, the grand valley extends over 3,000 kilometers long, spans as much as 600 kilometers across, and delves as much as 8 kilometers deep. By comparison, the Earth's Grand Canyon in Arizona, USA 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 June 27 Carving Ma'adim Vallis Credit: R. Irwin III (CEPS/NASM,UVa), T. Maxwell, A. Howard, R. Craddock, D. Leverington Explanation: Just as erosion from the Colorado River carved the Grand Canyon on Earth, a river of flood water may have carved Ma'adim Vallis, one of the largest canyons on Mars. Researchers have presented strong evidence for such a scenario based on elevation data recorded by the MOLA (Mars...

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 31 In Chandor Chasma on Mars Credit: THEMIS, Mars Odyssey Team, JPL, NASA Explanation: Scroll right and dive into a spectacular canyon on Mars. This daytime infrared view, recently recorded by the THEMIS camera on board the orbiting Mars Odyssey spacecraft, covers a 30 by 175 kilometer swath running along the canyon floor. The north (left) end of the scene is poised at the edge of...