Do we really understand the Sun?

Solar 'Fireworks' Signal New Space Weather Mystery Jan 24/05


The most intense burst of solar radiation in five decades accompanied a
large solar flare on January 20, shaking space weather theory and
highlighting the need for new forecasting techniques. The solar flare
occurred at 2 a.m. ET, tripping radiation monitors all over the planet
and scrambling detectors on spacecraft within minutes. It was an extreme
example of a flare with radiation storms that arrive too quickly to warn
future interplanetary astronauts.

"The event also shakes current theory about the origin of proton storms
at Earth. "Since about 1990, we've believed that proton storms at Earth
are caused by shock waves in the inner solar system as coronal mass
ejections plow through interplanetary space," says Professor Robert Lin
of the University of California at Berkeley, principal investigator for
the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). "But
the protons from this event may have come from the Sun itself, which is
very confusing."

"The origin of the protons is imprinted in their energy spectrum (as
measured by ACE and other spacecraft), which matches the energy spectrum
of gamma-rays thrown off by the flare (as measured by RHESSI). "This is
surprising", says Lin, "because in the past we believed that the protons
making gamma-rays at the flare were produced locally and the ones at the
Earth were produced instead by shock acceleration in interplanetary
space. The similarity of the spectra suggests that they are the same."

"It means we really don't yet understand how the Sun works," says Lin,
"and we need to continue to operate and exploit our fleet of
solar-observing spacecraft to identify how it works."

Mo
http://www.nasa.gov/vision/universe/...fireworks.html
http://grb.sonoma.edu/index.php
http://sec.noaa.gov/today.html
http://projects.nrl.navy.mil/secchi/main.html
http://soleil.ssl.berkeley.edu/
http://sec.gsfc.nasa.gov/