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Making Unique Observations in a Very Cluttered World

Tuesday 8 February 2011

The largest digital colour picture ever of the night sky goes online - built from more than a trillion pixels -

The largest digital colour picture ever of the night sky goes online - built from more than a trillion pixels - 


The data used to create this photograph captures “the name of every galaxy in the observed universe, its position in the sky, its colour, its shape. In all, 144 pieces of information for every single one of the 500 million galaxies.”

The largest digital colour picture ever made of the night sky is built from more than a trillion pixels.
It would take 500,000 high-definition TVs to see the image at full resolution.
And that, Dr. Bob Nichol of the University of Portsmouth told the Star on Tuesday, is only a fraction of what’s really out there.
Beyond the half-billion galaxies – captured on the free downloadable images released by theSloan Digital Sky Survey III – are what he can only call “a lot more” – the other 90 per cent of the still-unobserved universe.
Still, the swirling blues and greens, the ominous red elliptical swarms, and the glittering gases against a tweedy-looking backdrop of sky are capturing “a tremendous surge of interest,” Nichol said with delight.
While the pictures fire the imagination, the accompanying comprehensive data on what might be the world’s largest spread sheet is intriguing professional and amateur astronomers.
That data captures “the name of every galaxy in the observed universe, its position in the sky, its colour, its shape. In all, 144 pieces of information for every single one of the 500 million galaxies.”
Scientists have seized on the numbers for two reasons: to find the odd, unexplained, undiscovered parts of the cosmos; and to find the patterns.
“Imagine if you have half a billion objects – one or two of them can be quite strange,” said Nichol, a cosmologist and spokesman for SDSS III. “That’s how quasars were detected in the 1970s.”
Among the patterns is the “rather simplified” knowledge that all galaxies are of two types: our own blue spiral Milky Way full of young stars, and red elliptical galaxies studded with old stars.
“Why are there two types? Astronomers are tacking that one still. I use the analogy: Why are there only men and women?”
While the SDSS III terapixel achievement creates a core of data that can be used for decades for research, Nichol expects it may be transcended in 10 years by a video of the known universe, rather than just a still picture.
That, he said, would mean Earthlings could watch “asteroids move and super novas go off. Technology isn’t there yet, but it will be.”
How reliable is one still picture of things light years away?
“The good news is that most objects don’t change in time. Galaxies are quite boring and tend to stay the same for a couple of billion years. Stars change, galaxies don’t.”
The image was started in 1998 using what was then the world’s largest digital camera, at 138-megapixels, attached to a 2.5-metre telescope at the Apache Point Observatory in New Mexico.
The camera is being retired to the Smithsonian as part of its astronomy collection.

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