Monday, February 18, 2008
Scientists Discover Earth-like Planet That Could Hold Life
Scientists say there may be many more worlds in our galaxy
For the last several years, scientists have been discovering new planets elsewhere in the universe at an astonishing rate. Now a group of researchers who have surveyed a large group of stars similar to our own Sun say that potentially life-supporting rocky planets may in fact be extremely common in the Milky Way, circling anywhere from 20 percent to 60 percent of Sun-like stars.
Using the Spitzer Space Telescope, the researchers looked for signs of hot dust at distances plausible for planet formation around various stars, categorized by age.
They found that warm dust at that distance was relatively common around stars that were 10 million to 20 million years old, but that it fell off almost entirely by the time stars were about 300 million years old.
That's about the right time scale to correspond with the time the Earth and other planets are believed to have formed slowly through the collision of smaller bodes, out of the Sun's own dust cloud. Here's University of Arizona astronomer Michael Meyer, who led the study:
"We don't often see warm-dust around stars older than 300 million years. The frequency just drops off. That's comparable to the time scales thought to span the formation and dynamical evolution of our own solar system," he added. "Theoretical models and meteoritic data suggest that Earth formed over 10 to 50 million years from collisions between smaller bodies."
A separate study found dust that some believe is attributable to the process of planet formation around stars that were just 10 million to 30 million years old.
The data can be interpreted different ways. At worst, it appears to show that at least one out of five Sun-like stars has the potential for forming rocky planets, they said. An optimistic interpretation might be that some massive discs of dust would form planets more quickly – and in that case, up to 62 percent of stars could be planet-forming.
But either way, the data seems to show there are plenty of other planets out there.
Earth-Like Planets May Breed Life
New evidence suggests more than half the Sun-like stars in the Milky Way could have similar planetary systems.
University of Arizona scientists, using NASA's Spitzer space telescope, have discovered that between 20 percent and 60 percent of the stars orbiting many sun-like stars in our galaxy were similar to planet Earth, increasing the possibility of finding extraterrestrial life.
These stars have favorable conditions for forming rocking planets like Earth able to hold life, according to the study presented by school astronomer Michael Meyer.
He said more studies were needed to determine which of these stars possibly hold extraterrestrial life, Meyer told the annual meeting of the American Association for the Advancement of Science on Monday.
Meyer and his team studied six group of stars that resemble our sun and sorted them by age, with the youngest estimated between 10 and 30 million years and the oldest between a billion and three billion years old
A similar search for extraterrestrial life is currently being conducted by the European Space Administration's Darwin mission. The agency's Technology Research Program has sponsored the development of critical optical components whose frictionless mechanism can respond to the touch of a feather.
The mission is aimed at discovering extrasolar planets and whether their atmospheres can sustain life.
Posted by SANJIDA AFROJ at 8:43 PM