Sunspots have been meager this year. As we approach the minimum of the 11-year sunspot cycle, solar activity is ebbing. That’s why it’s so exciting to see a big sunspot blemish the sun’s face these past few days. Amateur astronomer Giorgio Rizzarelli of Trieste, Italy sent along his photos to share the news when it was too cloudy to view the sun from my area. Now that it’s clear, I can see it myself.
I used a #14 welder’s glass and with only a little effort, spotted a pinhead-sized dot on an otherwise blank sun this morning. If you still have your eclipse glasses from the August 2017 eclipse, put ’em on and have a look. A clear sky is best, but it should still be visible if you have high, thin clouds like I did. Cup your hands around the glasses to block any stray light and concentrate your vision. It will appear very tiny but distinct. Always use a safe, approved filter when viewing the sun. If you see the spot or not, please share your observation by leaving a comment.
Although the sunspot looks like a little bug in the photos, it’s truly gigantic with a diameter about three times that of the Earth. Slicing across its middle is a skinny light bridge 12,400 miles (20,000 km) long and about 500 miles (800 km) wide or a bit shy of the length of Nebraska.
The bright appeared a couple days ago and threatened to split the spot in half. That may yet happen or the gap could close. Light bridges typically form during the breakup of sunspots. It should make for fun and instructive viewing the next few days to watch which way the core trends.
Sunspots are regions where concentrated magnetic fields deep within the sun rise to its surface and insulate and chill the area. Spots appear only dark because they’re several thousand degrees cooler than the blinding white surface. If you could see a sunspot apart from the sun it would glow with a brilliant orange-red light.
The dark umbra makes a depression in the sun’s surface like a valley. A light bridge then is literally a bridge of fire (hot like the rest of the bright solar surface) crossing a dark, colder abyss — an awesome thing to contemplate and even better to see for yourself.
Solar activity like flares and sunspots rises and falls in a cycle that averages 11 years. Right now, we’re near the bottom of that cycle, one of the reasons it’s exciting to see the big spot. Minimum is expected to occur sometime between July 2019 and Sept. 2020 with the next maximum due in 2023-2026. The coming minimum may last years so get ready for a lot of “blank suns.”
The last maximum in 2012-2014 was pretty wimpy as maxima go, and the next isn’t expected to be much better. While that may be good news for satellites and power grids, which can be adversely affected by powerful solar storms, aurora watchers prefer stormy times. That doesn’t mean auroras will dry up and go away. Coronal holes — openings in the sun’s magnetic canopy — are more common at minimum and produce auroras, too. But there’s nothing like a huge flare to spark a wicked display.
Meantime, we’ll be keeping an eye on the current spot. It will be nicely placed for viewing for the next 5 days or so. While it has produced minor B-class flares, it may have more in the offing.