On August 1, an entire hemisphere of the sun erupted.
Violent explosions on the sun erupt on a phenomenal scale – one that envelopes the entire star – and are linked by massive magnetic threads that stretch across hundreds of thousands of miles, a new study finds.
Solar flares, coronal mass ejections and other dramatic solar storms can go off all at once across virtually the entire sun, a team of researchers announced Dec. 13. The discovery suggests scientists should expand their studies of space weather to go beyond looking just at isolated parts of the sun, as has been common in the past.
This wider perspective could make forecasting space weather more difficult initially, but it should improve accuracy over the long haul, researchers said.
"To predict eruptions, we can no longer focus on the magnetic fields of isolated active regions," said study co-author Alan Title of Stanford University and Lockheed-Martin's Advanced Technology Center in Palo Alto, Calif., in a statement. "We have to know the surface magnetic field of practically the entire sun." [Gallery: Amazing Sun Photos]
The researchers presented their findings during a press conference here at the fall 2010 meeting of the American Geophysical Union.
A global solar explosion
The research team analyzed a massive explosion that took place on the sun on Aug. 1, 2010. An entire hemisphere of the sun erupted, sending shock waves racing across the solar surface and gigantic clouds of hot gas billowing into space.
The event was recorded in great detail by several NASA spacecraft — the Solar Dynamics Observatory and the twin STEREO (Solar Terrestrial Relations Observatory) space telescopes. Barely two-thirds of the event was visible from Earth, yet the spacecraft caught all of it from their complementary vantage points in space, researchers said. [Solar Tsunami: The Aug. 1, 2010 sun storm]
As a result, the scientists were able to see, study and connect the various, widely separated explosions. Researchers have known for decades that solar flares tend to bloom synchronously across vast distances. But the existence of these so-called "sympathetic flares" had been deduced mainly from statistical arguments, researchers said, not actual observations of the events as they occurred.
So the new data should open a new window into scientists' understanding of the sun, researchers said.
"We're not seeing everything [from Earth]," co-author Karel Schrijver, of Lockheed Martin's Solar and Astrophysics Lab in Palo Alto, told reporters today. "We have to expand our view and look well beyond the region exploding."
The scientists aren't sure exactly how the explosive events are connected, and what the underlying triggers may be. That's one of the next steps in the research, they said.
Improving space-weather forecasting
The more holistic view of the sun should improve scientists' forecasts of space weather, researchers said
Solar flares and coronal mass ejections (CMEs) — similar events that throw off powerful plumes of energy and charged particles — can interfere with radio and GPS signals on Earth. The events can affect airliners' communications with the ground, as well as a variety of other technological applications.
So getting a better handle on where and why these explosive events occur on the sun is key, researchers said. The new information should help out in this regard.
"These new discoveries help us understand the mechanisms of how and why solar flares and CMEs erupt from the sun, which in turn will improve our ability to predict these eruptive events," said Rodney Viereck, a scientist at the National Oceanic and Atmospheric Administration's Space Weather Prediction Center in Boulder, Colo.
To really improve their predictions, Viereck said, forecasters will have to incorporate physics-based models based on our improving understanding of the sun.
And this may take some time. Viereck compared space-weather forecasters' situation today to that faced 50 years ago by meteorologists seeking to understand Earth's weather. Back then, meteorologists were just beginning to introduce physics-based models into their calculations.
However long it takes, updating our understanding of the sun's violent tendencies is key, since the Earth orbits so close to its unpredictable parent star, researchers said.
"We live in the outer atmosphere of our star," said Lika Guhathakurta, SDO program scientist at NASA Headquarters in Washington, D.C. Getting a better understanding of space weather "is really necessary. It's not a choice for spacefaring nations like ours."
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