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Monday, June 21, 2010

Solar Dynamics Observatory's photos of the sun show end of solar minimum

A Sleeping Giant Awakens
Carl Parker, On-Camera Meteorologist, The Weather Channel, June 16, 2010
Timing is everything. And for the Solar Dynamics Observatory, launched into orbit this past February, the timing couldn't have been better. The SDO helps scientists study solar storms, and for a long couple of years prior to the launch, those storms were few and far between.

Our nearby star was in a deep sleep, largely devoid of the sunspots, flares and prominences that indicate heightened magnetic activity. And while such lulls have historically occurred every 11 years or so, this past solar minimum was exceptionally quiet and long-lasting --- fifteen months longer than average. That prompted some to wonder if we were entering a prolonged downturn, the most dramatic of which can affect climate.

But this year our sun has come back to life, with spectacular outbursts of magnetism and light that arc into loops many times the size of the earth. And the SDO has shown us these prominences with a new and startling level of detail:

March 30, 2010, courtesy NASA

The SDO has sophisticated instruments and high-resolution spectrometers that were developed to give us a greater understanding of the sun-earth environment, or space weather, which can affect our lives more than many would suspect.

Most commonly we see coronal mass ejections of lesser magnitude; they create remarkable shows in the high latitudes, where the solar streams are "collected" by the magnetism of the earth's poles. Solar particles collide with molecules in the upper reaches of the atmosphere, exciting them to the point of illumination, and creating the wondrous displays known as auroras:

courtesy NASA

But occasionally solar storms are much stronger. In 1859, a solar superstorm called the Carrington Event fired up brilliant auroras that awakened people who had mistaken the lights for sunrise. The auroras blanketed the globe, all the way down to the tropics. And there were widespread telegraph system failures,though not necessarily for lack of power; operators were stunned to find the devices still working after they were unplugged!

Now, think about how much the world has changed since 1859.

A report by the National Academy of Sciences outlined the vast potential for damage from a similar storm today. Writes Dr. Tony Phillips, "smart power grids, GPS navigation, air travel, financial services and emergency radio communications can all be knocked out by intense solar activity. A century-class solar storm, the Academy warned, could cause twenty times more economic damage than Hurricane Katrina."

Twenty times. And that's where the SDO comes in. Because it's able to monitor the sun with as Dr. Phillips says, "unprecedented spectral, temporal and spatial resolution", it's a powerful tool for scientists who hope to predict solar flares. The SDO is watching our sun 24/7, and scientists always have a detailed picture of how solar activity is evolving.

June 7, 2010, courtesy NASA

And there are other satellites that provide some lead time; the twin Solar Terrestrial Relations Observatory spacecraft monitor the far side of the sun, so flares won't surprise us when coming around the sun's horizon. And the Advanced Composition Explorer has been on patrol since 1997. It gives utility and satellite operators as much as 30 minutes before a powerful CME strikes; in that time, parts of the power grid can be disconnected to minimize the surge potential, and satellites can be put in safe mode, which shields them to an extent.

Thus far solar cycle 24 has not been particularly intense, and some scientists at the recent American Astronomical Society meeting say that it could be half as strong as the last three cycles. There's a lot to learn though. "Space weather forecasting is still in its infancy," says Thomas Bogdan of NOAA's Space Weather Prediction Center. "But we're making rapid progress."

You can keep up with the sun's daily activity at

courtesy NASA

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