Much like tornado watchers look to the skies for clues that a twister is
forming, NASA and university scientists are watching the Sun in an effort to
better predict space weather – blasts of particles from the Sun that impact
the magnetosphere, the magnetic bubble around the Earth.

Based at the National Space Science
and Technology Center (NSSTC) in Huntsville, Ala., this research unites scientists
from NASA’s Marshall Space Flight Center in Huntsville and the University of
Alabama in Huntsville.

Like severe weather on Earth, severe
space weather can be costly.

When massive solar explosions, known
as coronal mass ejections, blast through the Sun’s outer atmosphere and plow
toward Earth at speeds of thousands of miles per second, the resulting effects
can be harmful to communication satellites and astronauts outside the Earth’s
magnetosphere. On the ground, the magnetic storm wrought by these solar particles
can knock out electric power.

A study by scientists at the National Space Science and Technology Center,
published in the April 20 issue of the “The Astrophysical Journal,” is offering
new insight on these solar storms and how to better predict them.

One of the authors, Dr. David Falconer, a research associate from the University
of Alabama in Huntsville, compares potential solar-storm prediction techniques
to methods used for predicting thunderstorms and tornadoes on Earth.

“When we look up at clouds, we can identify those with
the potential to bring severe weather,” he explains. “If the sky is clear,
or filled with hazy Cirrus clouds, there is a low likelihood of severe weather.
On the other hand, we can use special equipment to observe the surface of the
Sun, enabling us to glean clues on what severe space weather might be forming.”

Fortunately, people on Earth aren’t without protection
from space weather. “Our planet’s magnetosphere protects us from the worst
of a solar storm’s fury,” says NSSTC solar scientist Dr. Ron Moore of the Marshall
Center.

Filled by charged particles trapped in Earth’s magnetic
field, the spherical comet-shaped magnetosphere extends out 40,000 miles from
Earth’s surface in the sunward direction and more in other directions. “But
when severe particle streams slam against the magnetosphere, we see the effects,”
Moore adds.

This NSSTC research builds on the 1999 “S marks the
spot” finding, made by researchers at Montana State University-Bozeman and the
Solar Physics Research Corporation in Tucson. They discovered that regions
of the Sun with an obvious global twist to the magnetic fields are more likely
to erupt in a coronal mass ejection than regions with no discernable global
twist.

In short, these ejections occur when solar magnetic
field lines snake around each other, forming the letter “S”. Usually, they
go past each other. But if they connect, it’s like a short circuit. The mid-section
breaks loose and drives out a coronal mass ejection.

Using the Solar Vector Magnetograph, a solar-observation
facility at the Marshall Center, NSSTC scientists monitored active areas of
strong magnetic fields on the Sun, measuring the amount of magnetic energy stored
in a region.

“Whereas a visible “S”-shaped structure in a magnetic region is only a qualitative
indicator of substantial stored magnetic energy, the vector magnetograph gives
a quantita-tive indicator, telling which of two “S”-shaped regions has the greater
energy,” says Moore.

This led NSSTC scientists to identify a correlation
between stored energy and coronal mass ejections. Areas with high levels of
magnetic energy were more likely to produce solar eruptions than areas with
low levels.

“In seeking predictions of solar activity, zero global
nonpotentiality is the space-weather version of a clear sky on Earth,” Falconer
says. “Regions with high global nonpotentiality have a large store of free
magnetic energy available for producing coronal mass ejections.”

With improvements in solar-storm prediction methods,
scientists are looking to the future, when new advancements may offer the opportunity
to issue solar-weather “watches,” similar to tornado watches.

“A tornado watch indicates the conditions are favorable
for the formation of a tornado, while a tornado warning indicates a tornado
has already been sighted,” Falconer explains. “Right now, we’re learning what
signs to look for as indicators of potential severe space weather.”

This advance warning will give people on Earth more time to prepare by placing
satellites in a safe configuration, planning the best time for astronaut space
walks or rocket launches, and implementing contingency plans to deal with any
power outages.

In addition to Falconer and Moore, solar scientist Dr. Allen Gary of the
Marshall Center also co-authored the study. The three researchers are part of
the NSSTC solar physics group, which develops instruments for measuring the
magnetic field on the Sun. With these instruments, the group studies the origin,
structure and evolution of the solar magnetic field and the impact it has on
Earth’s space environment.

A collaboration that enables scientists, engineers
and educators to share research and other facilities, the NSSTC is a partnership
with the Marshall Center, Alabama universities and federal agencies. It focuses
on space science, Earth sciences, materials science, biotechnology, propulsion,
information technology and optics.

The NASA role in this solar physics research project is led by the Marshall
Space Flight Center for the Office of Space Science at NASA Headquarters in
Washington, D.C.