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New Solar Telescope Would Focus on Sunspots, Storms

John Roach
for National Geographic News
December 21, 2004
 
If you thought predicting the weather on Earth was difficult, try forecasting the weather on the sun.

Like the Earth, the sun is subject to bouts of stormy weather. When these solar storms flare up, they can wreak havoc on Earth, causing power outages and disrupting satellite communications.

Because scientists remain fuzzy on the details of what drives the sun's weather, it is difficult to forecast.

A proposed telescope may change that. Known as the Advanced Technology Solar Telescope (ATST), the new instrument would "offer an unprecedented view of the sun," said Aimee Norton, a solar physicist with the High Altitude Observatory at the National Center for Atmospheric Research in Boulder, Colorado.


As planned, ATST would be the world's largest optical solar telescope. The instrument would be equipped with state-of-the-art technology that would allow scientists to zoom in on fine-scale, short-lived features found in the solar atmosphere.

"The ATST represents the biggest jump in solar light-gathering power of any telescope since the days of Galileo," said Jeff Kuhn. The solar scientist is an ATST co-investigator based at the University of Hawaii's Institute for Astronomy in Honolulu.

The project remains in the proposal stage. Scientists must decide where to place the telescope and secure funding to construct and operate it. Backers hope to build the telescope in Haleakala, Hawaii.

"We just need to go into detailed consideration to make sure everything will work there," said Dave Dooling, the outreach and education officer at the National Solar Observatory in Sunspot, New Mexico. The observatory is leading the ATST project proposal.

The telescope could be operational by 2010, according to the project team, provided international scientific funding agencies approve the final site selection and required construction funds.

Sunspots

Norton, the High Altitude Observatory solar physicist, specializes in the study of sunspots. She said ATST should reveal how sunspots are structured and how the strength of their magnetic fields are amplified and dispersed.

Sunspots are dark areas seen on the surface of the sun. They occur where regions of intense magnetic field emerge from inside the sun and extend outward to the solar surface. While sunspots play an integral role in the sun's weather, scientists do not yet fully understand how.

"Sunspots are related to geomagnetic storms, because when the sun has more sunspots, more [solar storms] occur," Norton said. "But it is not as simple as [noting that] if there is a large sunspot, a storm will occur."

Sunspots appear as dark patches, because they are cooler than other regions on the surface of the sun. The temperature differences are caused by intense magnetic fields, which suppress convective motions that transport heat out toward the sun's atmosphere.

"Sunspots are believed to be small pieces of much larger magnetic field residing in the solar interior," Norton said.

Scientists believe sunspots emerge like loose loops of thread, known as flux ropes, from the larger magnetic field inside the sun. The intersection of the thread with the solar surface (think of a rainbow touching the horizon) creates a sunspot pair.

Sunspots occur in cycles of increasing and decreasing activity that last approximately 11 years. The last sunspot cycle peaked in 2000. The next cycle is expected to begin in 2005 or 2006.

Solar Storm

Current research suggests that sunspots with complex magnetic geometries, such as twists and shears, culminate in solar storms, which are known as coronal mass ejections and solar flares.

During a storm, magnetic clouds of charged particles are ejected into space. Sometimes Earth intercepts these clouds, which affect Earth's magnetic field and the surrounding environment.

"Charged particles saturate and deform the configuration of Earth's magnetic field," Norton said. "This induces current in power lines, causing large-scale power outages. When satellites experience direct hits from charged particles, they can be damaged and lose communication abilities."

If constructed, ATST may provide further details on the conditions that give rise to solar storms, allowing researchers to make more informed weather forecasts.
 

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