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.”

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 1,000 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

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 most aspects of the mission,
including the science instrument, spacecraft integration and
environmental testing, and spacecraft operations and data

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.

A movie of the flare recorded by the RHESSI spacecraft is
available on the Internet at:

RHESSI data are now available online to the general public

More information about Sun-Earth Day can be found on the
World Wide Web at: