AR 12192 is a sunspot first spotted on Oct. 18, lingering into view for a couple of weeks before slipping out recently. It's about the size of Jupiter, making the sunspot so large that in can be observed from Earth without using a telescope.
During the time AR 12192 was observable from the planet, it shot out 10 solar flares, six of which were X-class types and four of which were of the M-class variety. However, the sunspot did not release any coronal mass ejections (CMEs) or powerful bursts of plasma.
"You certainly can have flares without CMEs and vice versa, but most big flares do have CMEs. So we're learning that a big active region doesn't always equal the biggest events," said solar scientist Alex Young from NASA's Goddard Space Flight Center.
Project scientist Dean Pesnell from Goddard's Solar Dynamics Observatory said that spotting similar flares from the same active region offers a good case study.
"This is important for one day improving the nation's ability to forecast space weather and protect technology and astronauts in space," explained Pesnell.
Sunspots are measured using micro-hemispheres, with one micro-sphere equivalent to around 600,000 square miles. AR 12192 was 2,750 MH in size, making it the 33rd largest sunspot out of about 32,000 that have been observed since 1874. It is also the largest since the AR 6368 was spotted on Nov. 18, 1990, which measured 3,080 MH.
To prove that the size of a sunspot may not necessarily be proportional to the solar flares it is capable of is the one that caused the Carrington event on Sept. 1, 1859. This particular sunspot unleashed the biggest solar flare ever recorded but it wasn't the biggest, not even making it to the top 50 with just 2,300 MH.
Given AR 12192's size, it may be possible to see the sunspot again when the active region faces the Earth once more in about two weeks. While there's no guarantee of this, larger sunspots have historically stayed observable after the sun turns. For those interested in catching AR 12192, eclipse glasses are needed. Never look at the sun directly to avoid serious eye damage.
As active regions on the sun, sunspots are formed when magnetic field lines become warped and twisted. Some part may break out, showing up on the surface as a sunspot. AR 12192 and all other sunspots are darker than the sun because they are cooler in temperature than the area around them.
