NASA Goddard Space Flight Center on line News Releases
NOW PLAYING AT A STAR NEAR YOU: THE LARGEST SUNSPOT IN TEN YEARS BLAZES AWAY WITH ERUPTIONS

Largest sunspot in 10 years as viewed by SOHO

Click on image to enlarge

A huge sunspot as big as the surface area of thirteen Earths is growing on the Sun and has now rotated with the Sun to face the Earth. The sunspot, in the region designated AR 9393, is the largest of the current solar cycle, making it the biggest to appear in ten years. This region also has been a prolific generator of stormy solar activity, hurling clouds of electrified gas towards Earth, producing four explosions, called flares, and spawning storms of high-speed particles in space.

The largest of the four flares occurred at 9:57 UT Thursday, March 29 and was rated as an X-class flare, the most potent designation. The other three flares were rated M-class, second only to the X-class. An eruption near AR 9393 hurled a cloud of electrified, magnetic gas towards Earth on Wednesday. This eruption, called a Coronal Mass Ejection (CME), may cause auroral (northern and southern lights) displays and magnetic storm activity when it impacts the Earth's magnetic field sometime Friday. Another Earthbound CME associated with the X-class flare was seen at 10:26 UT March 29, and is expected to arrive on Saturday.

"Sunspots with complex magnetic field structures like those in AR 9393 can generate big flares, and sure enough, we just had a powerful X-class flare from this area," said Dr. Joseph Gurman, NASA project scientist for the Solar and Heliospheric Observatory spacecraft, one of a fleet of sun-observing spacecraft now tracking this region and its activity.

Sunspots are darker areas on the visible surface of the Sun caused by a concentration of distorted magnetic fields. The strong magnetic field slows down the flow of heat from the

Sun's interior and keeps sunspots slightly cooler than their surroundings, causing them to appear dark. The number of sunspots increases and decreases as the Sun's 11-year cycle of stormy activity rises and falls. Violent solar activity is believed to be caused by the release of magnetic energy, and powerful solar eruptions like CMEs and flares often occur near the enhanced magnetic field of sunspots.

Solar flares, among the solar system's mightiest eruptions, are tremendous explosions in the atmosphere of the Sun capable of releasing as much energy as a billion megatons of TNT. Caused by the sudden release of magnetic energy, in just a few seconds flares can accelerate solar particles to very high velocities and heat solar material to tens of millions of degrees.

CMEs are clouds of electrified, magnetic gas weighing billions of tons ejected from the Sun and hurled into space with speeds ranging from 12 to 1,250 miles per second (about 20 to 2,000 kilometers per second). Depending on the orientation of the magnetic fields carried by the CME cloud, Earth-directed CMEs cause magnetic storms by interacting with the Earth's magnetic field, distorting its shape and accelerating electrically charged particles (electrons and atomic nuclei) trapped within.

Severe solar weather is often heralded by dramatic auroral displays, but magnetic storms are occasionally harmful, potentially disrupting satellites, radio communications, and power systems.

Both CMEs and flares are capable of producing storms of high-velocity particles. CMEs are believed to produce longer particle storms than flares, storms that sometimes last for days, as they plow through the slower solar wind at supersonic speeds, creating a shock wave that accelerates electrically charged subatomic particles.

A NASA video file with movies and images of this sunspot will be broadcast on NASA TV Friday, March 30. For more information on the sunspot, refer to: http://www.spaceweather.com/

NASA TV DETAILS:

GE2 satellite
Transponder 9C
85 degrees west longitude
3880 MHZ Video frequency
6.8 MHZ Audio frequency
Vertical polarization

Broadcast every 3 hours starting at 12:00 p.m. EST                 


Last Updated 03/30/01
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