for National Geographic Today
Tools like the Hubble Space Telescope have given astronomers a new view of the cosmos, allowing them to gaze deep into the universe to observe far-off galaxies. But a new digital telescope here on Earth has opened a revelatory view of the universe as well as our own galactic neighborhood.
In 2001, an international consortium of about 200 astronomers began the Sloan Digital Sky Surveythe largest international astronomical survey ever undertaken--using a specialized telescope atop a peak in New Mexico's Sacramento Mountains.
Their mission: to map one-quarter of the entire universe out to 1 billion light years from Earth by 2005. It is expected that Sloan will find 500 million galaxies and a slightly larger number of starsand will accurately chart their positions in the heavens.
"Sloan has changed the way that astronomers do astronomy," says Michael Turner, a cosmologist at the University of Chicago. "With Sloan, you can look at millions of objects: the structure of a galaxy or the universe."
The telescope was designed to see a much wider area of the sky than other telescopesand uses new digital imaging technology and computer software to detect the dim, older stars that telescopes using photographic techniques missed. The universe contains many more of these faint stars than bright, hot stars.
Finding New Stars Close to Home
At last week's meeting of the American Astronomical Society meeting in Seattle, some of the excitement focused on discoveries much closer to home, including a previously unseen circle of stars surrounding the Milky Way.
What we uncovered was numerous stars that seemed to be where they didn't belong," says Brian Yanny, an astronomer at Fermi National Accelerator Laboratory in Batavia, Ill.
"The Milky Way resembles a big Frisbee," Yanny says. "We kept seeing these hot blue stars at a constant distance from the center of the galaxy that seemed to form a ring."
The ring was hidden from view behind stars and gases on the same visual plane as the Milky Way. But Sloan's digital cameras observe objects in the sky that appear in various colors according to their composition.
"These stars were bluer than stars of our sun's population, which are yellow or red," Yanny says. "This suggests that they were created at a different time or out of a different batch of gas."
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