NASA's Chandra finds saturn reflects X-rays from sun

Erica Hupp/Dolores Beasley
Headquarters, Washington May 25, 2005
(202/358-1237/1753)

Steve Roy
Marshall Space Flight Center, Huntsville, Ala.
(Phone: 256/544-0034)

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

RELEASE: 05-134


NASA'S CHANDRA FINDS SATURN REFLECTS X-RAYS FROM SUN

When it comes to mysterious X-rays from Saturn, the ringed planet may
act as
a mirror, reflecting explosive activity from the sun, according to
scientists
using NASA's Chandra X-ray Observatory.

The findings stem from the first observation of an X-ray flare reflected
from
Saturn's low-latitudes, the region that correlates to Earth's equator and
tropics.

Dr. Anil Bhardwaj, a planetary scientist at NASA's Marshall Space Flight
Center
(MSFC), Huntsville, Ala., led the study team. The study revealed Saturn acts
as a
diffuse mirror for solar X-rays.

Counting photons, particles that carry electromagnetic energy including
X-rays,
was critical to this discovery. Previous studies revealed Jupiter, with a
diameter 11 times that of Earth, behaves in a similar fashion. Saturn is
about
9.5 times larger than Earth. It is twice as far from Earth as Jupiter.

"The bigger the planet and nearer to the sun, the more solar photons it will
intercept; resulting in more reflected X-rays." Bhardwaj said. "These
results
imply we could use giant planets like Jupiter and Saturn as remote-sensing
tools.
By reflecting solar activity back to us, they could help us monitor X-ray
flaring
on portions of the sun facing away from Earth's space satellites."


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Massive solar explosions called flares often accompany coronal mass
ejections,
which emit solar material and a magnetic field. When directed toward Earth,
these
ejections can wreak havoc on communications' systems from cell phones to
satellites.

Even as the research appeared to solve one mystery, the source of Saturn's
X-
rays, it fueled long standing questions about magnetic fields. Of the three
magnetic planets in our solar system, Jupiter and Earth emit two general
types of
X rays, auroral emissions from polar regions and disk emissions from low
latitudes. No research has observed unambiguous signatures of auroral X-ray
emissions on Saturn.

"We were surprised to find no clear evidence of auroral X-ray emissions
during
our observations," Bhardwaj said. "It is interesting to note that even as
research solves some mysteries, it confirms there is much more we have to
learn."

The research appeared in the May 10, 2005 issue of Astrophysical J. Letters.
the
research team also included Ron Elsner of MSFC; Hunter Waite of the
University of
Michigan, Ann Arbor; Randy Gladstone of the Southwest Research Institute,
San
Antonio, Texas; Thomas Cravens of the University of Kansas, Lawrence; and
Peter
Ford from the Massachusetts Institute of Technology, Cambridge.

Bhardwaj is working at MSFC as a National Research Council scholar. MSFC
manages
the Chandra program for NASA's Science Mission Directorate in Washington.
Northrop Grumman of Redondo Beach, Calif., was the prime development
contractor
for the observatory. The Smithsonian Astrophysical Observatory controls
science
and flight operations from the Chandra X-ray Center in Cambridge, Mass.

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

http://www.nasa.gov/home/index.html




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Jacques :-)

www.spacepatches.info