Chandra Looks Back At The Earth (Forwarded)

Steve Roy
Marshall Space Flight Center, Huntsville, Ala. December 28, 2005
(256) 544-6535

Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
(617) 496-7998

CXC Release: 05-10

Chandra Looks Back At The Earth

In an unusual observation, a team of scientists has scanned the northern
polar region of Earth with NASA's Chandra X-ray Observatory. The results
show that the aurora borealis, or "northern lights," also dance in X-ray
light, creating changing bright arcs of X-ray energy above the Earth's
surface.

While other satellite observations had previously detected high-energy
X-rays from the Earth auroras, the latest Chandra observations reveal
low-energy X-rays generated during auroral activity for the first time.

The researchers, led by Dr. Ron Elsner of NASA's Marshall Space Flight
Center in Huntsville, Ala., used Chandra to observe the Earth 10 times
over a four-month period in 2004. The images were created from
approximately 20-minute scans during which Chandra was aimed at a fixed
point in the sky and the Earth's motion carried the auroral regions
through Chandra's field of view.

From the ground, the aurora are well known to change dramatically over
time and this is the case in X-ray light as well. The X-rays in this
sample of the Chandra observations, which have been superimposed on a
simulated image of the Earth, are seen here at four different epochs.

Auroras are produced by solar storms that eject clouds of energetic
charged particles. These particles are deflected when they encounter the
Earth¹s magnetic field, but in the process large electric voltages are
created. Electrons trapped in the Earth¹s magnetic field are accelerated
by these voltages and spiral along the magnetic field into the polar
regions. There they collide with atoms high in the atmosphere and emit
X-rays. Chandra has also observed dramatic auroral activity on Jupiter.

Dr. Anil Bhardwaj of Vikram Sarabhai Space Center in Trivandrum, India, is
the lead author on a paper describing these results in the Journal of
Atmospheric and Solar-Terrestrial Physics. Dr. Bhardwaj was a
co-investigator on this project and worked with Dr. Elsner at NASA's
Marshall Space Flight Center while this research was conducted.

The research team also includes Randy Gladstone (Southwest Research
Institute, San Antonio, Texas); Nikolai Østgaard (University of Bergen,
Norway); Hunter Waite and Tariq Majeed (University of Michigan, Ann
Arbor); Thomas Cravens (University of Kansas, Lawrence); Shen-Wu Chang
(University of Alabama, Huntsville); and, Albert E. Metzger (Jet
Propulsion Laboratory, Pasadena, Calif).

NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra
program for the agency's Science Mission Directorate. The Smithsonian
Astrophysical Observatory controls science and flight operations from the
Chandra X-ray Center in Cambridge, Mass.

Additional information and images are available at:

http://chandra.harvard.edu/photo/2005/earth/
and
http://www.nasa.gov/centers/marshall/news/chandra/

For information about NASA and agency programs on the Web, visit:

http://www.nasa.gov