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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 December 16 Night and Day in Melas Chasma on Mars Credit: Arizona State U., JPL, NASA Explanation: What types of terrain are found on Mars? Part of the answer comes from thermal imaging by the robot spacecraft 2001 Mars Odyssey currently orbiting Mars. The above picture is a superposition of two infrared images, a black and white image taken during Martian daylight and a false-color image taken...

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 28 Earth's Richat Structure Credit: Landsat 7, USGS, NASA Explanation: What on Earth is that? The Richat Structure in the Sahara Desert of Mauritania is easily visible from space because it is nearly 50 kilometers across. Once thought to be an impact crater, the Richat Structure's flat middle and lack of shock-altered rock indicates otherwise. The possibility that the Richat Structure was formed by a volcanic...