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To: average joe who wrote (3675)	11/21/2006 1:54:14 PM
From: one_less	Respond to of 5290

Granny was an alien... ========================= Interstellar organic molecules suggest that Earth may have been seeded by the cosmos. By Kathryn Garfield DISCOVER Vol. 27 No. 11 \| November 2006 \| Space Interstellar clouds of gas are impregnated with organic molecules, the chemical ingredients of life. In just two years of work with the Robert C. Byrd Green Bank Telescope, astronomers have discovered eight new organic molecules near the center of the Milky Way, bolstering theories that key chemical precursors of life were first forged in deep space. All eight of the new carbon-containing molecules are relatively large, composed of 6 to 11 atoms each. One of the molecules, acetamide, is particularly exciting because it contains a peptide bond, the essential bond for connections between amino acids. "No one has ever found an amino acid in space," says Jan M. Hollis of NASA's Goddard Space Flight Center. "I've actually written several papers about not finding them." Interstellar clouds of gas are impregnated with organic molecules, the chemical ingredients of life. In just two years of work with the Robert C. Byrd Green Bank Telescope, astronomers have discovered eight new organic molecules near the center of the Milky Way, bolstering theories that key chemical precursors of life were first forged in deep space. All eight of the new carbon-containing molecules are relatively large, composed of 6 to 11 atoms each. One of the molecules, acetamide, is particularly exciting because it contains a peptide bond, the essential bond for connections between amino acids. "No one has ever found an amino acid in space," says Jan M. Hollis of NASA's Goddard Space Flight Center. "I've actually written several papers about not finding them." The Robert C. Byrd Green Bank Telescope in West Virginia is tuning in to faint radio emissions from organic molecules in the far reaches of our galaxy. The new finds join a list of about 125 smaller carbon-based molecules identified in space so far. All of them tend to form by simple chemical reactions between smaller components or through the activity of radicals and neutral molecules on the surface of floating dust grains. Eventually, energy from nearby protostars causes the molecules to evaporate off the dust and fly end over end through space, where astronomers can trace their radiation frequencies, since each molecule radiates in a distinctive way. In the famous Miller-Urey experiment of the 1950s, researchers produced a rich soup of amino acids by running an electric current through flasks containing elements of a primitive Earth, thus showing how precursor chemicals could have formed here. But the discovery of biologically significant molecules in interstellar clouds of gas and dust could push life's history much, much farther back in time and out into space. "When you look at these clouds, it's almost like looking back into history," Hollis says. Molecules like these, traveling on interplanetary dust, meteorites, or comets, "could give life a jump-start on an early planet."

To: average joe who wrote (3675)	11/21/2006 2:18:45 PM
From: one_less	Read Replies (2) \| Respond to of 5290

Dark Matter Made Visible There's far more to the universe than meets the eye. By Alex Stone DISCOVER Vol. 27 No. 11 \| November 2006 \| Space Most of the universe, it may surprise you to know, is invisible. About 80 percent of all matter is "dark," emitting no light and interacting with normal matter only through gravity.Or that's what physicists have long suspected, without direct proof. Then two massive colliding galaxy clusters in the constellation Carina caught the attention of Marusa Bradac of the Kavli Institute at Stanford University and her colleagues, who saw this cosmic smashup as a chance to watch dark matter in action. Bradac and her colleagues compared X-ray pictures of visible matter in the clusters with measurements of their total mass. As the clusters collided, the visible matter (red) appeared to be kicked out of alignment with the overall mass (blue). If dark matter didn't exist, the separation in the image couldn't occur. "The visible matter gets stuck there, whereas the dark matter goes through unaffected," she says. Dark matter (blue) passed through nearly unaffected after the head-on galactic collision, while visible matter (red) slowed down and spread out. Courtesy of NASA Until now, the best evidence for dark matter was that orbital speeds of stars in a galaxy do not fall off with increasing distance from the galaxy's center, as would seem to be necessary to keep the stars from flying off into space. The fact that the galaxies hold together suggests that unseen mass provides the gravity to hold them together. Some researchers have sought to explain the steady orbital speed with alternative theories of gravity, but it is unlikely that anything other than dark matter can explain the new observations. "It's pretty conclusive," Bradac says. Meanwhile, particle physicists are trying to detect dark matter on Earth. "There are dark-matter particles around you and me right now," Bradac says. "It's likely they will be detected in the next five years."