Telescope finds aurora borealis filled with X-rays
Monday, January 16, 2006
The orbiting Chandra X-ray telescope generally plucks secrets from far-flung galaxies and star clusters, but Huntsville scientists have used the telescope for the first time to look back on planet Earth.
Designed at Marshall Space Flight Center, Chandra was used to observe the aurora borealis, or northern lights. A team of researchers, led by Dr. Ron Elsner at the National Space Science and Technology Center in Huntsville, has discovered the lights emit not only a colorful dancing light show "but also different types of X-rays," Elsner said.
Photos from Chandra's observations show the northern lights dance in a night sky filled with intense color and bright X-ray arcs. Auroras are produced by the interaction of the sun with the Earth's atmosphere. Solar storms eject clouds of electrically charged particles that are deflected when they encounter Earth's magnetic field.
In the process, large electrical voltages are created, according to NASA. Electrons trapped in the Earth's magnetic field are accelerated by these voltages and spiral along the planet's magnetic field into the polar regions. There they collide with atoms high in the atmosphere and emit X-rays.
Elsner and teams of astronomers have worked with Chandra to observe auroral activity on Jupiter. The Chandra observations of Earth were made from December 2003 through April 2004. The scientists have spent the past two years reviewing their data to publish their discoveries.
Taking the X-ray snapshots of Earth called for some tricky, high-flying maneuvers on the part of the space telescope team.
"Because of its orbital path, Chandra could not be pointed directly at the Earth; it cannot follow Earth as it moves," Elsner said. "Chandra was pointed at a specific place, and we waited for the Earth to fly through that area."
The team made 10 observations that lasted 20 minutes each. "Which isn't a lot of time, but we did glean a lot of information," Elsner said.
Researchers usually use the $1.6 billion telescope to detect X-rays from stars and distant regions of space. But Chandra was used to detect X-rays emitted from the moon in 2003. Scientists hope this information will help them to better understand the moon's chemical composition.
Elsner hopes the 10 observations won't be the last time the North Pole's X-rays are studied by astronomers.
The team has received approval to use a European satellite - XMM Newton - to study the aurora borealis, Elsner said. "We still have to work out the details on how that will work," he said.
"We also plan to put in another proposal for Chandra, but time is highly valued on it," Elsner said. "We hope that, perhaps, 2007 will be the year we can use Chandra again."
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