NASA
CELEBRATES SUN-EARTH DAY WITH SOLAR X-RAY FIREWORKS
Just
in time for Sun-Earth Day, a new NASA spacecraft, complete
with a new name, made its debut by observing a huge explosion
in the atmosphere of the Sun. The blast, called a solar flare,
was equal to one million megatons of TNT and gave off powerful
bursts of X-rays.
The
solar fireworks were captured by what is now known as the
Reuven Ramaty High-Energy Solar Spectroscopic Imager spacecraft,
or RHESSI. The spacecraft launched last month as HESSI was
recently renamed in honor of Dr. Reuven Ramaty, who died in
2001 after a long and distinguished career in the Laboratory
for High Energy Astrophysics at the NASA Goddard Space Flight
Center, Greenbelt, Md. Ramaty was a pioneer in the field of
solar-flare physics, gamma-ray astronomy and cosmic rays.
"We
are thrilled to be making the first high-resolution movies
of flares using their high-energy radiation," said Brian
Dennis, the RHESSI mission scientist at Goddard. "We
want to understand how solar flares can explosively release
so much energy. RHESSI shows us the high-energy radiation
emitted by flares: their X-rays and gamma rays. This radiation
reveals the core of the flare -- the exact time and place
where the energy is released."
Today
is the second annual Sun-Earth Day, which is sponsored by
NASA's Sun-Earth Connection Education Forum to provide an
opportunity to learn more about the Sun's connection to the
Earth through images, cultural parallels and activities. Powerful
events on the Sun, including flares, occasionally disrupt
satellites and communications and power systems.
Scientists
believe solar flares are powered by the violent release of
magnetic energy, but how this happens is unknown. A new movie
features one of the first flares recorded by RHESSI, which
occurred Feb. 20 in the southern hemisphere of the Sun, an
active region designated "AR 9830."
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It
was a moderately powerful flare, classified as M2.4 by the
National Oceanic and Atmospheric Administration (NOAA). The
most powerful flares, designated X-class by NOAA, can release
up to 100 times more energy.
During its planned two-year mission, RHESSI will study the
secrets of how solar flares are produced in the Sun's atmosphere.
Launched Feb. 5, RHESSI is now fully operational after only
six weeks in orbit. It is observing the Sun and recording
the high-energy radiation from solar flares as they occur.
RHESSI
is the first NASA Small Explorer mission being managed in
the "Principal Investigator" mode. The Principal
Investigator, Robert Lin of the University of California,
Berkeley, is responsible for many aspects of the mission,
including the science instrument, spacecraft integration and
environmental testing, and spacecraft operations and data
analysis.
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The
RHESSI scientific payload is a collaborative effort among
the University of California, Berkeley; Goddard; the Paul
Scherrer Institut in Switzerland; and the Lawrence Berkeley
National Laboratory in Berkeley. The mission also involves
additional scientific participation from France, Japan, The
Netherlands, Scotland and Switzerland.
The
Explorers Program Office at Goddard manages the RHESSI mission
for NASA's Office of Space Science in Washington. Spectrum
Astro, Inc. of Gilbert, Ariz., constructed the RHESSI spacecraft
and provided integration support.
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