by Annette Trinity-Stevens
If you want to predict the weather, you might walk outside and look at the sky. Is it clear or is it cloudy? If you see clouds, are they dark and ominous, suggesting rain, or are they puffy and white?
Scientists have the same kind of interest in space weather, and now they think they have a tool for forecasting some spectacular eruptions that come from the sun.
"These are the largest explosions in the solar system - full stop - and now we may be able to predict them,"said Richard Canfield, a research professor of physics at MSU.
Canfield, MSU research scientist David McKenzie and a colleague in Japan found a strong correlation between an S-shaped pattern on the sun and the likelihood that an explosion will occur in that region within days. The S-shape is like a loaded gun that scientists now know has a high probability of going off.
Called coronal mass ejections because they come from the sun's corona or outer halo, the explosions are as powerful as billions of nuclear explosions, said Canfield.
The National Aeronautics and Space Administration, which paid for the study, highlighted the discovery for journalists at a March 9 "Space Science Update" at NASA headquarters in Washington, D.C. Canfield and two other scientists explained the finding to reporters during the press conference broadcast on NASA TV. Even before the new conference, Canfield and McKenzie were getting calls from the national media as word of the announcement began to circulate.
The explosions can hurl up to 11 billion tons of hot, electrically charged gas into space. The outbursts occur several times a day, but only those shot toward Earth are potentially dangerous, Canfield said. They travel the 93 million miles between the sun and Earth in about four days and can damage orbiting satellites,communications networks and pipelines.
The ejections can be bad news for power companies as well, because they can turn multi million electrical systems into what one utility called "fried green transformers."
On the other hand, they create the striking light shows known as the aurora borealis or northern lights.
Canfield and McKenzie made the discovery by looking at two years' worth of daily X-ray images from a satellite called Yohkoh. The composite pictures - about 50 images for each day - were made into movies.
Samantha Allen, a student from Harlem High School, helped the scientists comb through the data last summer. She was on campus for the Montana Apprenticeship Program for Native American students.
The project not only showed that "S" marks the spot of a likely eruption, it also showed a correlation between large sun spot areas and explosions. Sun spots are cool, black areas on the otherwise bright solar disk.
A scientific paper on the discovery was published this month, but the scientists said more work must be done before the S-shaped tool is a precise one. Going back to the rain cloud analogy,McKenzie said the research is at the point of being able to tell which are the rain clouds and which aren't.
"The next step is to say, 'This cloud is going to burst on this day'," he said.
NASA official George Withbroe said the MSU-Japan discovery will be useful to the burgeoning science of space weather, which aims to predict solar activity and its impact on Earth.
NASA is planning another mission to look at the ejections using two satellites, one lagging behind the other. And the National Oceanic and Atmospheric Administration is building a satellite similar to Yohkoh that is scheduled for launch next year, Canfield said.NOAA is the agency that would issue ejection warnings in the same way meteorologists make long-range forecasts on Earth, he added.
Annette Trinity-Stevens is the MSU Research Editor.