Newly Observed High-Altitude Auroras

[Lionel]

A recently launched Air Force satellite has detected auroras, those shimmering displays of colorful light, at altitudes far higher above Earth than previously known, confirming anecdotal reports from astronauts that scientists had previously dismissed.The auroras known as the northern or southern lights that are typically seen from Earth extend from about 60 miles to several hundred miles above the planet's surface. Now, cameras on the Air Force's Coriolis satellite launched early this year are also spotting auroras at altitudes above 500 miles. How they are produced is still a mystery."It's a relatively new aspect of this phenomenon no one has seen at this altitude," said David Webb, a research physicist at Boston College.Details were presented Wednesday at the fall meeting of the American Geophysical Union. Pulses of charged particles, mostly electrons, produce auroras when they are flung off by the sun and collide with molecules in the Earth's atmosphere. Previously, scientists believed the effect was limited to lower altitudes where the atmosphere is more dense. High above Earth, they believed, there simply weren't enough air molecules to create the effect.

As a result, astronauts' reports of seeing auroras dancing high above their space shuttles were routinely dismissed."They weren't believed," said Bernard V. Jackson, a solar physicist at the University of California, San Diego.

View: Full Article | Source: The Mercury News