BON VOYAGE, GAIA

On Dec. 19th, the European Space Agency launched one of the most ambitious astronomy missions ever: GAIA, an observatory that will survey more than one billion stars in the Milky Way. By the time GAIA's five year mission is over, astronomers will be able to build the first accurate three-dimensional map of celestial objects in our home galaxy. GAIA will do its work from the L2 Lagrange point approximately 1.5 million km from Earth. On Dec. 20th, amateur astronomer Dave Eagle of Higham Ferrers UK observed the spacecraft hurtling toward that distant station: 

"It was great to see the spacecraft in the exact position predicted, near the shield of Orion," says Eagle. "After watching the launch live on the Web in the morning, I was glad to be able to track it down and wish it well in its coming mission. It was much brighter than I expected, so its newly deployed Sun shield is doing a great job."

Once it reaches its L2 parking orbit and begins observing, GAIA will log the position, brightness and color of every star that falls within its field of view. By repeating these observations throughout its mission, astronomers will be able to calculate the distance, speed and direction of motion of each star GAIA sees, chart variations in their brightness, and determine whether they have nearby companions.

This kind of detailed information about the Milky Way is unprecedented and may lead to important new discoveries about the evolution and structure of our galaxy. For updates about GAIA, stay tuned to the ESA.                       www.spaceweather.com

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