We saw solar activity tick up in late October, but this past week the sun has become even more agitated with the appearance of a giant sunspot at least five times larger than the Earth and a powerful M-class solar flare that occurred early on Nov. 29. It was the largest flare recorded in 3 years.
The smallest flares are A-class, followed by B, C, M and X. Similar to the Richter scale for earthquakes, each letter represents a 10-fold increase in energy output. An M-class flare is ten times more powerful than a C and 100 times the strength of a B. X-class flares are the most energetic. Even though Sunday's flare detonated on the sun's far side, the blast created a spectacular display that spilled into view along the edge of the sun. A phenomenal group of loop prominences — fiery hydrogen gas tracing powerful magnetic fields — formed over the location soon after.
Had the flare been directed toward the Earth I'd be telling you to watch for a fine display of northern lights in the next couple nights. Sadly, it pointed away from our planet. We must be patient. The blast occurred inside a brand new sunspot group that's just now coming into view. If the group continues to seethe and boil with activity we may yet get our chance for a bright aurora.
There's never been a better time than now to own a safe solar filter. I say that because there's a large sunspot visible with the naked-eye when using a proper filter. It looks like a very small, dark fleck or dot below the center of the bright disk. If you bought a pair of eclipse glasses for the 2017 solar eclipse, they're perfect. You can also call a welding supply store in your area and ask if they carry a #14 welder's glass (only #14 is safe, do not substitute with a #13). That's my favorite tool.
NEVER look directly at the sun without protection. The proper way to observe is to first place the welder's glass or eclipse glasses over your eyes and then look up at the sun. When you're done, turn away first and then remove the filter. Doing it this way you'll never have to worry about inadvertently catching a glimpse of raw sunlight. Stars seem tiny and fragile at a distance but up close they demand respect.
Naked-eye sunspots aren't common, so I hope you're able to seize the opportunity to see this monster. Today (Nov. 30) it's a little past square-on. Assuming the spot doesn't break up and dissolve it could remain visible for about another five days or so.
Sunspots are dark because they're areas of highly concentrated magnetic energy on the sun's surface, called the photosphere. Magnetic fields insulate those regions from the heat bubbling up from below, cooling them and making the spots appear darker in contrast. But make no mistake, sunspots are still hot, hot, hot — around 6,500° F compared to 10,000° F (3,600-5,500° C) for the photosphere.
Speaking of aurora, there's a modest chance a minor geomagnetic storm on the night of Dec. 1 for skywatchers living in the northern U.S. and Canada. The bright moon, which rises around 5:30 p.m. local time that evening, will likely swamp anything but a bright display. But you never know. The aurora sometimes overperforms.
We're currently climbing out of solar minimum, a time of very low solar activity (few sunspots and flares) that bottomed out in December 2019. It heartens all sun-watchers and aurora lovers to see the sun hit the ground running again.
"Astro" Bob King is a freelance writer for the Duluth News Tribune. Read more of his work at duluthnewstribune.com/astrobob.