Astro Bob: Cyclopean sunspot turns Earth's way

Solar activity is on the rise, with 10 sunspot groups visible on Wednesday. One of them is a real giant.

Big sunspot
On Wednesday, the sun displays 10 sunspot groups, including Region 3190, dominated by the huge sunspot near the center of the disk.
Contributed / NASA, SDO

Please sky, clear up! Not only are all these clouds making it impossible to see Comet ZTF (C/2022 E3), but the sun is wild with spots I can't wait to get my eyes on. There are at least 10 separate sunspot groups visible at the moment (Jan. 18). One of them, Region 3190, hosts a spot so large you can see without any magnification at all.

Just cover your eyes with either a pair of safe (and undamaged) eclipse glasses or a #14 welder's glass and behold the black spot near the center of the solar disk. About five times the size of Earth, it possesses a messy magnetic field, the kind likely to spawn powerful M- and X-class flares.

Flares can cause shortwave radio blackouts here on Earth and potentially send batches of high-speed protons and electrons (basically cooked and disassembled hydrogen atoms) called coronal mass ejections flying our way. Under the right conditions, the material can swizzle its way down the planet's polar magnetic field lines and light up the skies with the northern and southern lights.

According to the latest space weather summary there's a slight chance for X-class flares over the coming three days. That makes me optimistic for potential auroras to turn up in the next week to 10 days. Observers in the Upper Midwest have reported several minor auroras in the past couple weeks due to heightened solar activity, but clouds have been so thick over the region, viewing has been limited. Let's hope that changes soon.

Big spot
An enormous sunspot about five times the size of Earth dominates the sun on Wednesday. It's big enough to see through a safe solar filter with just your eyes — no binoculars or telescope needed. The small orange "slice" in the dark, inner umbra is called a light bridge.
Contributed / NASA, SDO

Solar magnetism is concentrated in sunspots much like it is in a strong magnet. Sunspot groups even have magnetic poles, with part of the group acting as the positive (+) end of the magnet and the other the negative (-) pole. These strong magnetic fields insulate the surface from the heated bubbles of plasma rising up from below, making sunspots some 3000° cooler — and therefore darker — than the solar surface.


Sun on Jan. 14, 2023
Region 3190 with the big spot has staying power. Here it is on Jan. 14 when it first rotated around to the near side. The sun rotates on its axis about once every 27 days (4 weeks). In complex spots, the positive and negative magnetic "poles" can twist, turn and reconnect like the north and south poles of two magnets snapping together. That releases tons of energy and radiation into space.
Contributed / Bob King

Sunspots have two parts: a dark core called the umbra surrounded by a lighter, filamentary penumbra. Occasionally, narrow rifts appear in the umbra called light bridges. Their appearance can be a sign that the spot is starting to break apart and dissipate. While Region 3190 displays one such light bridge at the moment, it's been holding its own so far and doesn't appear to be in decay.

Sunspot predictions
The red curve in this graph shows the original prediction for the current solar cycle — Cycle 25 — which is expected to peak in July 2025. The purple curve and black zigzag show the actual activity level, which is considerably stronger than the prediction. Time in years is plotted along the bottom, with sunspot number on the left (vertical axis). The zigzag curve below the graph plots the highs and lows of previous 11-year cycles dating back to 1750.
Contributed / NOAA

Sunspots wax and wane in an cycle lasting about 11 years. At solar minimum, they're rare, but at maximum they can spread like a pox across the sun's face. Big, complex groups like 3190 often mean exciting times ahead.

Solar activity continues to defy original predictions, always good news for aurora watchers. While huge sunspots make us hopeful for auroras, they can peter out, too. Maybe that will happen with Region 3190. Either way, the monster sunspot is worth a look. It's incredible that something so enormous can also be so ephemeral, lasting just weeks.

If you don't own a filter, purchase a #14 welder's glass from your local welding supplier or check out the safe eclipse filters at Rainbow Optics and on Amazon .

Keep it handy! There's been close to a dozen naked-eye sunspot groups over the past year with more to come.

"Astro" Bob King is a freelance writer and retired photographer for the Duluth News Tribune. You can reach him at
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