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Eyes of WISE: NASA scope made by SDL completes sky survey

By Kim Burgess
The Herald Journal
July 17, 2010
Heart and Soul Nebulae

Seven Sisters Get WISE
This image shows the famous Pleiades cluster of stars as seen through the eyes of WISE, or NASA's Wide-field Infrared Survey Explorer. The mosaic contains a few hundred image frames -- just a fraction of the more than one million WISE has captured so far as it completes its first survey of the entire sky in infrared light. The Pleiades are what astronomers call an open cluster of stars, meaning the stars are loosely bound to each other and will eventually, after a few hundred million years, go their separate ways. The cluster is prominent in the sky during winter months in the constellation Taurus, when viewed from the Northern Hemisphere. Often called the Seven Sisters from Greek tradition, this cluster of stars has been named by cultures the world over: Parveen in Persian; Tianquiztli in the Aztec tradition, and Subaru in Japan. The Pleiades is even the logo of the automotive company that bears its Japanese name. In this infrared view of the Pleiades from WISE, the cluster is seen surrounded by an immense cloud of dust. When this cloud was first observed, it was thought to be leftover material from the formation of the cluster. However, studies have found the cluster to be about 100 million years old -- any dust left over from its formation would have long dissipated by this time, from radiation and winds from the most massive stars. The cluster is therefore probably just passing through the cloud seen here, heating it up and making it glow. At a distance of about 436 light-years from Earth, the Pleiades is one of the closest star clusters and plays an important role in determining distances to astronomical bodies further away. This picture from WISE covers an area of 3.05 by 2.33 degrees, which is the roughly the same area on the sky that a grid of six full moons by 4.7 full moons would occupy. Most of the stars in the cluster fall within the 20-light-year-wide region shown here. All four infrared detectors aboard WISE were used to make this mosaic. Color is representational: blue and cyan represent infrared light at wavelengths of 3.4 and 4.6 microns, which is dominated by light from stars. Green and red represent light at 12 and 22 microns, which is mostly light from warm dust.

An innovative NASA telescope constructed at Utah State University's Space Dynamics Lab will complete its first survey of the sky today - a project that has already led to the discovery of 25,000 asteroids.

Launched into orbit in December, the Wide-field Infrared Survey Explorer (WISE) has the ability to see previously undetectable celestial objects using infrared sensors that can pick up dim light.

The 1.3 million images it has produced so far include distant galaxies and brown dwarf stars, as well as 100,000 asteroids, which mainly occupy an area between Mars and Jupiter. About 90 of these space rocks travel "near" Earth, meaning roughly 30 million miles from the planet.

SDL employees are thrilled to see their project bearing such spectacular fruit.

John Elwell, WISE program manager at the lab, said some have hardly been able to tear themselves away from their computer screens.

"Every day is exciting," he added. "I'm proud that such a fundamental contribution to science comes out of Logan, Utah."

For the next three months, WISE will map half of the sky again, giving astronomers a look at what's changed.

The mission scans strips of space as WISE orbits around the poles following Earth's day-night line - meaning that as the planet moves around the sun, new areas come into WISE's field of view.

It has taken six months, or the amount of time for Earth to travel halfway around the sun, for the mission to complete one full scan of the entire sky.

"The eyes of WISE have not blinked since launch," said William Irace, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Both our telescope and spacecraft have performed flawlessly and have imaged every corner of our universe, just as we planned."

WISE's work will come to an end when its block of solid hydrogen coolant, needed to chill the infrared detectors, runs out, probably in November.

Images from $320-million device will help guide future missions like the James Webb Space Telescope to areas that warrant more research.

The first release of WISE data, covering about 80 percent of the sky, will be delivered in May of next year.

To view more images from WISE, go to www.nasa.gov/wise and http://wise.astro.ucla.edu.

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