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vineri, 6 septembrie 2013

Evidence Found for Planet-Cooling Asteroid 12,900 Years Ago

The dust refuses to settle on a debate about whether asteroid impacts caused one of Earth’s most famous cold snaps 12,900 years ago.

The latest evidence in the contentious discussion comes in the form of pieces of bedrock from Quebec, Canada, that seem to have been blasted out as far as Pennsylvania. “I’d say there’s evidence of an impact happening, for sure,” says Mukul Sharma, an isotope geochemist at Dartmouth College in Hanover, New Hampshire, and co-author of a study published this week in Proceedings of the National Academy of Sciences.

joi, 5 septembrie 2013

Gravity variations much bigger than previously thought

A joint Australian-German research team led by Curtin University's Dr Christian Hirt has created the highest-resolution maps of Earth's gravity field to date - showing gravitational variations up to 40 per cent larger than previously assumed.
Using detailed topographic information obtained from the US Space Shuttle, a specialist team including Associate Professor Michael Kuhn, Dr Sten Claessens and Moritz Rexer from Curtin's Western Australian Centre for Geodesy and Professor Roland Pail and Thomas Fecher from Technical University Munich improved the resolution of previous global gravity field maps by a factor of 40.

miercuri, 4 septembrie 2013

Milky Way Gas Cloud Causes Multiple Images of Distant Quasar

For the first time, astronomers have seen the image of a distant quasar split into multiple images by the effects of a cloud of ionized gas in our own Milky Way Galaxy. Such events were predicted as early as 1970, but the first evidence for one now has come from the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope system.

The scientists observed the quasar 2023+335, nearly 3 billion light-years from Earth, as part of a long-term study of ongoing changes in some 300 quasars. When they examined a series of images of 2023+335, they noted dramatic differences. The differences, they said, are caused by the radio waves from the quasar being bent as they pass through the Milky Way gas cloud, which moved through our line of sight to the quasar.

The Milky Way Supernova You've Never Heard Of

Every year astronomers see hundreds of supernovae erupt in other galaxies, but from such great distances these stellar explosions look only like bright dots. Researchers therefore prize the few supernovae that past observers witnessed in the Milky Way, where telescopes can scrutinize the wreckage. Since the year A.D. 1000, skywatchers have seen five of our galaxy's stars die in brilliant explosions. Now a new distance determination to the most mysterious of these is yielding new insight into its nature.