Stuff I Wrote Elsewhere

An update on the Sloan Digital Sky Survey (sub. req.):

Josh Frieman’s cosmic vacuum cleaner seems to be working.

Perched on a ridge in the mountains of southern New Mexico, the big Sloan Digital Sky Survey telescope spends its nights sucking down big swaths of sky.

In three months last fall, it found 142 Type Ia supernovas— distant exploding stars that are key to understanding the universe’s expansion.

Hunting supernovas is hard work. Previous surveys bagged fewer than a hundred in a good year. But by capitalizing on the Sloan’s unprecedented ability to sweep across and record vast areas of sky quickly and automatically, Frieman and his colleagues hope to fill in big gaps in our understanding of how the universe works.

“We actually are probing more volume of space than any other supernova survey,” said Frieman, an astronomer at the University of Chicago and Fermilab.

With the Sloan, “You can cover a big chunk of sky,” said Jon Holtzman, a New Mexico State University astronomer working on the supernova project.

“Big chunk of sky” might be an understatement to describe what the Sloan has accomplished.

In its first five years of work, the telescope catalogued an astonishing 215 million galaxies and stars. Scientists then determined the distance to a million of those, building the first true three-dimensional map of a big piece of the universe.

With additional funding from the Alfred P. Sloan Foundation and others, the project last summer was extended for another three years, giving scientists a crack at using the powerful telescope to answer new questions about the universe.

Frieman and his colleagues are among the beneficiaries, using three-month runs in the fall of 2005, 2006 and 2007 to try to help sort out puzzling questions about how fast the universe is expanding.