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Universe says “Cheese” for biggest ever astro-photo

SDSS1.jpgFraming a group shot can be difficult. Capturing half a billion stars and galaxies in one picture is – well – overwhelming.

Yet the Sloan Digital Sky Survey (SDSS), which has taken images of the night sky using a dedicated 2.5-m optical telescope at the Apache Point Observatory in New Mexico since 1998, managed to photograph this many objects for their latest release, SDSS III. The trillion-pixel snapshot is the largest sky image taken to date.

“It’s not just really big, it’s really useful,” says Michael Blanton, an astronomer from New York University in New York and member of the SDSS team, who presented the new results at the annual meeting of the American Astronomical Society (AAS) in Seattle, Washington on 11 January.

The image is filled with galaxies in the process of being born or crashing violently into one another, he says. Previous images released from SDSS have provided astronomers will many such interesting “needles in a haystack” that help them understand the stages of galactic evolution, he adds. The latest release allows them to search a substantially bigger haystack, he says.


The extra detail also allows researchers to see deeper and fainter objects in the universe. By calculating the positions of such distant galaxies relative to one another, the team has built a three dimensional map of the nearby universe, says David Schlegel, an astronomer from the Lawrence Berkeley National Laboratory in Berkeley, California . So far, the collaboration has mapped galaxies in 3D out to around a billion light years from Earth. When the project completes identifying the positions of objects in the new data in 2014, they will have mapped out galaxies to 7 billion light years away, he says.

Objects at this distance are younger than half the age of the universe and will allow researchers to understand how the distribution of matter in the universe has changed over time. In particular, the team is interested in mapping out baryonic acoustic oscillations, a standard unit of measurement that helps give researchers a sense of the large-scale structure of the universe, says Blanton. The results may bring new insights into the nature of both dark matter and dark energy, says Schlegel.

More locally, the data will help astronomers understand the origin of our own galaxy, says Constance Rockosi, an astronomer from the University of California, Santa Cruz. Researchers have used previous SDSS data to identify bright bands of old stars in the Milky Way. Such objects are fossil remnants of the dwarf galaxies that our Milky Way consumed during its growth, she says. With better detail from SDSS III, astronomers can get a more complete picture of how our galaxy grew and evolved over time, she says.

The results are available publicly starting 11 January on the SDSS website’s Skyserver and will be incorporated into the Galaxy Zoo, a citizen science project that uses thousands of volunteers to identify objects in astronomers’ images.

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Image: SDSS

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