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 quantitative 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.
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