Big sunspots have been few and far between on the sun in recent weeks. But there sure have been lots of smaller ones. On most sunny days I set up a small, filtered telescope to see what the sun’s up to. Solar observing is incredibly fast and easy — telescope, safe filter placed securely over the front lens, tripod, and you’re good to go.
Contributed / Bob King
On March 16 it looked someone had sprinkled bits of dirt across the sun. I counted 13 different sunspot groups that day using a magnification of 27x. None of them displayed any impressive spots, at least compared to the behemoths of last summer. But their sheer number made an impression.
Sunspots are sites on the sun where magnetic energy is strongly concentrated. They’re dark because they’re about 3,500 degrees cooler than the surrounding 10,000-degree surface. Strong magnetic fields — like those around an ordinary bar magnet but thousands of times more intense — inhibit the flow of hot gases from the solar interior, insulating and chilling the area. Chill is a relative term. Despite their dark appearance, spots are still around 13 times hotter than a very hot oven.
Contributed / NASA (left and center), Bob King (right)
At first glance, it may look like the spots are randomly scattered across the sun, but most gather in groups. Some groups stand alone and are easy to tell apart. For others it takes a little experience to see where the border of one ends and a new one starts.
Each group’s members are magnetically linked to each other, with one section acting as the north pole of a magnet, and the other as the south pole. Each bunch is assigned a number so we can keep track of it as the sun slowly rotates on its axis once approximately every 4 weeks.
Astronomers have been counting spots systematically since 1847, but useful data goes back to the early 1600s. Sunspot number is a good indicator of overall solar activity. Flares and coronal mass ejections are frequently connected to sunspot groups, so the more spots — and the more complex sunspot groups become — the better the chances for solar storms to occur. And that means increasing chances to see the northern lights.
Counting them is easy enough, but there’s a twist. Astronomers tally both individual sunspots and groups. Each group is assigned a value of 10 spots. In the photo there are 13 groups, so 13 multiplied by 10 is 130. Next, you add in the number of individual sunspots. I counted 40. Together, the total sunspot number for March 16 comes to 170. That’s a high number and indicative of strong solar activity.
When formally submitting sunspot tallies, an observer also has to multiply their result by a small factor depending on observing conditions and equipment. By counting sunspots with a small, filtered telescope, arriving at what the monthly average is, and plotting the result on a piece of graph paper, the ups and downs of the 11-year solar cycle will appear right before your eyes.
Contributed / NASA, NOAA, ISES
Or you can have the professionals do it. They count sunspots, average monthly numbers and lay it all out on a curve to look for trends. They also study historical patterns and include data like how much radio energy the sun produces, which fluctuates throughout the solar cycle. Before every new cycle they gather and make a prediction of when the next peak, called solar maximum, will occur.
The original forecast for the current cycle, dubbed Cycle 25, was made in 2019 with the peak predicted for this upcoming July. However, more recent forecasts hint that we reached maximum in late 2024, so we may have already passed the peak. A more definitive answer will have to wait until the sun enters a slump. Then we’ll be able to look back with hindsight and better frame the time.
Contributed / Bob King
In the meantime, enjoy the sun’s busy period while you can by catching the northern lights. On Friday night, March 21, we had a fine display in the Duluth region. A stronger storm is forecast for Saturday night, March 22. If the sky stays clear, go out as early as 9 p.m., look north from a dark location, and you might just see arcs and rays dance across the northern sky. I’ll post updates on my Facebook page at facebook.com/astrobobking.
“Astro” Bob King is a freelance writer and retired photographer for the Duluth News Tribune. You can reach him at nightsky55@gmail.com.
