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Thu March 15, 2012
Arizona Telescope Sets New Standard For Optical Astronomy
A telescope in Arizona has taken some of the clearest pictures ever of distant celestial objects, including the first images of the innermost planet in a planetary system 127 light years from Earth. They achieved this astronomical tour de force using something called adaptive optics, a technique that eliminates the blurring caused by the Earth's atmosphere.
Having to peer through the atmosphere is a major disadvantage of ground-based telescopes compared with orbiting telescopes like the Hubble Space Telescope. But Earth observatories have one major advantage: they can use much larger mirrors to gather light. For example, Hubble has a single light-collecting mirror less than 8 feet in diameter. The Large Binocular Telescope in Arizona has two primary light-gathering mirrors, each 27.5 feet in diameter. The larger the mirrors, the fainter and smaller the object a telescope can see.
Until now, that size advantage was negated by atmospheric turbulence that causes light to spread out, creating a blurry image of stars. But adaptive optics is changing all that. The LBT system analyzes the light distortion caused by the air above the telescope, and then corrects for that distortion by using a second mirror system that can change its shape 1,000 times per second to compensate for the atmospheric turbulence.
"With this unrivaled new technology, we can now probe the close-in environments of nearby stars with a clarity that was previously not possible," says Richard Green, Director of the LBT. For example, LBT was able to see a fourth planet in the system known as HR8799, an object that was predicted to exist but hadn't been seen before. It was also able to deduce that the planet probably has a cloud covering masking it's methane atmosphere.
Here's a video that shows it in action:
"It's incredible that we can now learn so much about these distant worlds, when a short time ago directly imaging extrasolar planets was still a dream," said University of Arizona astronomer Andy Skemer.
The LBT is an international collaboration. Partners include: The University of Arizona, Istituto Nazionale di Astrofisica, Italy, the Max Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University, The Ohio State University, The University of Notre Dame, University of Minnesota and University of Virginia
(Joe Palca is a correspondent on NPR's science desk.)