The idea that Mars once had oceans is a controversial one: It's been proposed before, and formations that look like shorelines have been found in images from a variety of spacecraft.
Now scientists, after analyzing data from the European Space Agency's Mars Express mission, have concluded that the northern plains of Mars may have had an ocean.
Mars Express' MARSIS radar, deployed in 2005, penetrates deep into the Martian surface. Scientists from the Institut de Planétologie et d’Astrophysique de Grenoble and University of California, Irvine, say that the first 60 to 80 meters of the planet's subsurface shows evidence of sedimentary material and ice, indicating that an ocean could have existed there.
Scientists are proposing not just one, but two possible oceans in the same area. The first ocean would have existed 4 billion years ago when Mars was warmer.
The second would have existed 3 billion years ago after Mars sustained an ice-melting impact. It would have been temporary since the water either refroze or vaporized into the atmosphere.
Evidence of oceans in this case doesn't indicate life, however, the scientists say. The second, temporary ocean probably wouldn't have existed long enough to sustain life, the French institute's Dr. Jérémie Mouginot said in a statement. To find life, astrobiologists will have to study parts of Mars' history when water may have existed for longer periods of time.
Europe's deadly cold snap may have a lot to do with shrinking amounts of ice in the Arctic, a recent study suggests.
Nearly 300 deaths have been reported across the continent, with snow accumulations not seen in five decades reported in some places. Warsaw, Poland, has seen 11 days of temperatures well below average, with a coldest reading of 35 below zero Fahrenheit.
"Vital clues about the devastating ends to the lives of massive stars can be found by studying the aftermath of their explosions. In its more than twelve years of science operations, NASA's Chandra X-ray Observatory has studied many of these supernova remnants sprinkled across the galaxy.
The latest example of this important investigation is Chandra's new image of the supernova remnant known as G350.1+0.3. This stellar debris field is located some 14,700 light years from the Earth toward the center of the Milky Way.
Evidence from Chandra and from ESA's XMM-Newton telescope suggest that a compact object within G350.1+0.3 may be the dense core of the star that exploded. The position of this likely neutron star, seen by the arrow pointing to "neutron star" in the inset image, is well away from the center of the X-ray emission. If the supernova explosion occurred near the center of the X-ray emission then the neutron star must have received a powerful kick in the supernova explosion.
Astronomers from the Carnegie Institution of Washington and the University of California, Santa Cruz, have announced yet another planet that may theoretically be fit for life. It's called GJ667Cc.
Its mass is 4.5 times that of the Earth, but that's still small in the grand scheme of things - planets found outside our solar system are typically larger. In fact, scientists say, it could be made from rock instead of gas.