Active region 2192 (AR 2192) is about the same size as the planet Jupiter or 87,000 miles end to end. This illustration is based on a photo of the sunspot group taken October 22. Click for more information and animations. Credit: NASA/SDO/Alex Young
Wow, have you ever? Look at that sunspot group. If it seems bigger than any you’ve ever seen you’re right. At least in the last five years. Active region 2192 is the largest sunspot group recorded so far in Solar Cycle 24 which began in 2009. Solar cycles typically last about 11 years and chart the rise and decline of sunspots, flares and other solar activity.
The giant spot group 2192 faces Earth squarely today and should look spectacular during this afternoon’s partial solar eclipse. Here we see many cooler, darker umbrae surrounded by the lighter penumbrae. The group has a magnetically complex beta-gamma-delta magnetic field ripe for flaring. Credit: NASA/SDO
Yesterday I grabbed my #14 welder’s glass and couldn’t believe how easy it was to see this behemoth. If you have a filter ready for today’s partial solar eclipse, use it to look at the sun anytime, and you’ll see what I mean.
Rarely do naked eye sunspots look like more than dark dots. Region 2192 stands apart. Look carefully through your filter and you’ll discern that the left side (eastern half) looks darker than the western side. That’s because most of the darker bits, called umbrae, are concentrated there.
The sun this morning Oct. 23 with our featured sunspot group facing toward Earth. Credit: NASA/SDO
Sunspots have two parts – a dark core (or cores) called an umbra surrounded by a pale, skirt-like penumbra. Each spot group marks a region on the sun’s fiery outer skin where magnetic energy is concentrated. The magnetic forces that permeate the Sun are the same as those that flow the magnets on your refrigerator but contain vastly more energy because they cover huge regions of the Sun’s surface or photosphere.
Strong magnetic fields within a sunspot group quell the turbulent churning of the photosphere, chilling the region by several thousand degrees. Sunspots appear dark against the Sun’s blazing disk because they’re cooler. If you could rip them away from the Sun and see them alone against the sky, they’d be glaringly bright.
The crazy big sunspot group unleashed an X-class flare around 9 a.m. October 22 seen in these photos taken in two “flavors” or far ultraviolet light by NASA’s Solar Dynamics Observatory. Credit: NASA/SDO
Twisty fields of magnetic energy looping above sunspots can become unstable in the hot, turbulent environment of the Sun’s surface, which bubbles and boils like overcooked oatmeal in a microwave oven, and release their pent-up power in violent explosions called solar flares.
2192 has been no stranger to flares. Harboring a complex beta-gamma-delta magnetic field where the magnetic “north poles” and “south poles” lie side by side, they practically beg to explosively reconnect. Since Monday, the spotted beast has spewed two X-class (most powerful) and 8 M-class (medium strength) flares. So far though, none has been directed toward the Earth.
Watch the big group rotate onto the sun’s face and grow in the 72-hour animation made with NASA’s Solar Dynamics Observatory
That’s likely to change very soon since the group is now squarely facing the planet. Already, NOAA’s space weather forecast calls for a 95% chance for more M-class and 55% chance for X-class flare in the next 24 hours. Space weather is expected to be strong during the same period. That might mean auroras coming around as soon as this evening. I’ll keep you posted.
Not only will the sun be eclipsed this afternoon but the planet Venus shines just 1.1 degrees to its north. Venus is very close to superior conjunction which occurs early Saturday. In the photo, the planet is in the background well behind the Sun. Don’t count on seeing Venus – too much glare! This photo was taken from space by NASA’s Solar and Heliospheric Observatory this afternoon using a coronagraph to block the Sun from view. Credit: NASA/ESA
Good luck with today’s eclipse. If you need more information including viewing times for your city, please see my earlier blog on the topic.