MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
Contact: Jane Platt (818) 354-0880
FOR IMMEDIATE RELEASEJune 1, 1999
SPACE BLOBS CREATE SUPER-SPEEDY, BACKWARD AURORAS
Blobs of electrified particles spew violently from the Sun,
zoom at "warp speed" toward Earth's magnetic field, and trigger
an unusual form of aurora, scientists have discovered using an
ultraviolet camera on NASA's Polar spacecraft.
These electrified blobs, called coronal mass ejections,
travel at more than 1.5 million miles per hour, or 2,000 times
the speed of sound, and create interplanetary shock waves that
"ram into" Earth's magnetic field. This is roughly comparable to
the way a supersonic aircraft breaks the sound barrier and
creates a shock wave that we hear as a sonic boom. With the
aurora, the effect of the interplanetary shock wave is not heard,
but instead is seen as a multi-colored display by Polar.
The more common type of Earth aurora is formed through a
process that begins when the magnetic fields that extend from
Earth's Poles are dragged away from the Sun and Earth by the
solar wind. When these magnetic fields collide, they annihilate
each other and ultimately create a hot, electrified gas that
produces an eerie, colorful display near midnight at high and low
latitude locations such as Alaska and Antarctica. We call those
displays the northern and southern lights.
These newly discovered auroras appear in those same latitude
regions -- but unlike the better known auroras, they appear at
high noon, when they would usually be obscured by the Sun. That
would explain why no one on Earth has reported seeing them yet.
In addition, these dayside auroras move much, much faster and in
the opposite direction from ordinary auroras.
"This sheds new light on the way the Sun's tumultuous
activities affect us here on Earth," said Dr. Bruce Tsurutani of
NASA's Jet Propulsion Laboratory, co-investigator for the Polar
camera. "Since this type of aurora has not been seen by
earthlings, it's a prime example of a robotic spacecraft finding
things we'd never know about otherwise."
"Originally NASA's Wind spacecraft was used to find
interplanetary shocks," said Dr. Xiaoyan Zhou, a National
Research Council resident research associate who is also on the
Polar science team. "We wanted to find out what effect these
shocks have on Earth. We were surprised to discover that they
caused these unusual, fast-moving auroras." Polar's instruments
confirmed their existence with a dozen sightings. These latest
aurora findings were based on data gathered during the past two
Now that scientists are aware of the new form of auroras,
they hope professional and amateur Earth observers will look for
the phenomenon at certain locations like Spitzbergen, Norway in
the winter, when the skies are dark at noon. "We're anxious to
know what these new auroras look like when seen from Earth,"
More will be learned about these space blobs, or coronal
mass ejections, when NASA's planned Solar Probe spacecraft flies
closer to the Sun's sizzling surface than any previous
spacecraft. Solar Probe will launch in 2007 and will approach to
a distance of only 1-1/2 times the Sun's diameter in 2010,
surviving temperatures above 3,700 degrees Fahrenheit.
"I can hardly wait to see close-up pictures of a coronal
mass ejection when the spacecraft flies through one as it's being
formed," said Tsurutani, who also serves as Solar Probe project
The Polar and Wind missions are managed by Goddard Space
Flight Center, Greenbelt, MD, for NASA's Office of Space Science,
Washington, DC. The two spacecraft are part of the International
Solar-Terrestrial Physics program. Solar Probe is managed by JPL
as part of the Outer Planets/Solar Probe project. JPL is a
division of the California Institute of Technology, Pasadena, CA.
For a picture go to http://www.jpl.nasa.gov/releases/99/aurora.pdf.
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