Sunspots and Solar Flares

A sunspot is a cooler, and therefore darker, region of the Sun's photosphere caused by a solar magnetic disturbance. Strong, dense magnetic fields generated by circulating plasma sometimes become entangled and surge through the photosphere, creating the sunspot. The knot causes the temperature to fall to around 1000 K in the sunspot region, which darkens the photosphere. The dark center of the sunspot is called the umbra, and it is surrounded by a dim filamentary area called the penumbra. Sunspots range from Earth-size "pimples" to swollen scars halfway across the surface. Sunspot activity generally follows an 11-year cycle, called the "sunspot cycle." A solar flare is a violent eruption of plasma from the chromosphere of the Sun that is whipped up by intense magnetic activity. During the eruption, flares rise thousands of kilometers above the chromosphere, and the plasma temperatures quickly soar to 20 million degrees. Large flares release 10^25 Joules, or about the energy of a few million volcanic eruptions on the Earth. Sunspot and solar flare frequency are strongly related. In addition, flares often disturb the Earth's atmosphere electrically, thus interfering with radio transmissions. The aurora borealis and aurora australis are results of flare activity that injects energetic particles into Earth's magnetic field.

Resources

Our Star, the Sun By human standards, the Sun is eternal. It rises...

Featured Images

Composite image of the Sun
Hot Sun Wednesday, December 24, 2014
Superflare on one of the stars of DG Canum Venaticorum
Tiny Star, Big Outburst Wednesday, December 3, 2014
Three solar flares in early June 2014
Solar Fireworks Thursday, June 12, 2014
One of the first images from IRIS, a new Sun-watching satellite
First Sunlight Wednesday, July 31, 2013
A powerful solar flare erupts on March 6, 2012
Stormy Skies Thursday, March 8, 2012
A January 23, 2012 solar flare
Restless Sun Monday, January 30, 2012
The glow of the aurora from the International Space Station
Heavenly Lightshow Sunday, November 6, 2011
A solar eruption on June 7, 2011
Big Splash Tuesday, June 7, 2011
The Sun as seen from space
Close to the Sun Monday, January 3, 2011
Eruption of gas from the surface of the Sun
Sun Power Wednesday, December 22, 2010
Loopy Sun Friday, April 23, 2010

Radio Programs

Blackout! The Sun turns out the lights Wednesday, March 12, 2014
Under Attack Earth is attacked by a star Tuesday, October 29, 2013
Storm Probes Plunging into the danger zone Thursday, December 20, 2012
The Sun III Looking for the surface of the Sun Wednesday, December 19, 2012
Looking Deep Looking for storms before they’re born Monday, February 13, 2012
X Factor The Sun’s “X” factor Monday, October 10, 2011
Weather Forecasts Expanding the daily weather forecast Saturday, August 6, 2011
Space Weather Nasty weather from beyond Earth Friday, August 5, 2011
Dangerous Space One of the hazards of space travel Thursday, December 16, 2010
Quiet Sun II A calm and peaceful Sun Sunday, August 22, 2010
Quiet Sun The Sun stays unusually calm Saturday, August 21, 2010

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