If you have a small telescope equipped with a safe solar filter you should really take a look at the sun this week. There are lots of spots. If you don't have a filter you can still use the projection method illustrated in the photo below. Cut out a piece of cardboard and fit it over the instrument to cast a shadow. Then hold a sheet of paper in the shadow, aim and focus. Remember to never look directly at our daytime star or leave a telescope unattended when it's pointed at the sun.
Currently, four substantial sunspot groups give the sun a speckled egg appearance. All of them are easily visible in a small scope magnifying around 25x. A few of these dark patches are even bigger than the Earth. Solar magnetic fields are strongly concentrated in sunspots and insulate these regions from the rest of the sun's broiling surface called the photosphere. With a temperature about 3,000 degrees cooler than their surroundings, sunspots appear dark to our eyes, but they're still incredibly hot, about 6,700 degrees.
Extreme temperatures strip electrons from the sun's most common element, hydrogen and create a sea of positively charged protons and negatively charged electrons. These swirl and stream in the tremendous heat and generate magnetic fields in the process.
Magnetism and electricity are intimately linked. When you plug in an appliance, the current (made of electrons) moves through the wire and creates a magnetic field around the cord. You can detect the field with an ordinary compass. Likewise, a moving magnetic field will generate a current in a wire.
Solar magnetic fields within the sun grow stronger and stronger until they become buoyant, rise and break through at the surface as sunspots. Sunspots have magnetic poles just like a bar magnet. If the leading spot in a group points north, the region following the spot acts like the south pole.
Within a sunspot group, especially a rapidly-growing one, there may be more than one pair of poles in close proximity. Occasionally, a north pole with connect with a south pole. Think of it as two magnets snapping together. When it happens, a tremendous amount of magnetic energy is released in the form of a solar flare.
A modest flare produces the equivalent of several million 100 megaton hydrogen bombs. The blast can expel massive amounts of solar plasma (the mix of electrons and protons we talked about earlier) and magnetic field into space. If the explosion happens to be directed toward the Earth, the material will arrive anywhere from 15-18 hours to several days later depending on the severity of the detonation.
Most of the time these clouds of solar stuff just blow by the planet, but occasionally they can magnetically connect to Earth's own magnetic field . . . and the party begins! Electric currents generated by those moving fields can slingshot solar plasma into the upper atmosphere at speeds up to 45 million mph (724 million kilometers per hour).
Both protons and electrons get the zing, but it's mostly the lighter electrons, which are easier to speed up, that cause all the excitement. They smack into and energize oxygen and nitrogen atoms. When the atoms return to their previous relaxed state, they emit the green, red and blue light that create mind-boggling auroras.
Will that happen with any of the current sunspot groups? It's possible, but we'll just have to watch and wait. That's the fun of solar observing. You get to see one of the underlying causes of the northern lights. Then, if we do get aurora, you can point your finger at the perpetrator. Sunspot observing also demonstrates the sun's rotation.
At the equator, it takes only about 24 days to go around once. But in the polar regions the sun rotates more slowly — about once every 30-35 days. The sun is a ball of plasma, so it doesn't rotate rigidly like the rocky planets do.
If you have a telescope and lack a proper solar filter, check this excellent resource. You'll also find filters there for safe naked-eye observation. Since activity is now on the increase as the sun beelines to the next solar maximum around July 2025, this is a great time to start a regular program of safe and educational sun-watching.
"Astro" Bob King is a freelance writer for the Duluth News Tribune. Read more of his work at duluthnewstribune.com/astrobob.