Solar Activity and How Earth Feels About It

On August 1, 2010, an entire hemisphere of the sun erupted. Filaments of magnetism snapped and exploded, shock waves raced across the stellar surface, billion-ton clouds of hot gas billowed into space. Astronomers knew they had witnessed something big. It was so big that it may have shattered old ideas about solar activity.

For the past three months, Karel Schrijver has been working with fellow Lockheed-Martin solar physicist Alan Title to understand what happened during the “Great Eruption.” They had plenty of data: The event was recorded in unprecedented detail by NASA’s Solar Dynamics Observatory and twin STEREO spacecraft. With several colleagues present to offer commentary, they outlined their findings at a press conference today at the American Geophysical Union meeting in San Francisco.

Explosions on the sun are not localized or isolated events, they announced. Instead, solar activity is interconnected by magnetism over breathtaking distances. Solar flares, tsunamis, coronal mass ejections–they can go off all at once, hundreds of thousands of miles apart, in a dizzyingly-complex concert of mayhem. It has gotten to the point that is is a lot harder to predict eruptions based solely on the sun’s magnetic field, other factors now need to be calculated into the equation. This fact increases the work load for space weather forecasters, but it also increases the potential accuracy of their forecasts. The whole-sun approach could lead to breakthroughs in predicting solar activity, and would provide improved forecasts to customers such as electric power grid operators and commercial airlines, who could take action to protect their systems and ensure the safety of passengers and crew.
chrijver and Title broke down the Great Eruption into more than a dozen significant shock waves, flares, filament eruptions, and CMEs spanning 180 degrees of solar longitude and 28 hours of time.

At first it seemed to be a cacophony of disorder until they plotted the events on a map of the sun’s magnetic field. Further analysis may yet reveal the underlying trigger; for now, the team is still wrapping their minds around the global character of solar activity. One commentator recalled the old adage of three blind men describing an elephant–one by feeling the trunk, one by holding the tail, and another by sniffing a toenail. Studying the sun one sunspot at a time may be just as limiting.

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