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A respectable new sunspot has come into view on the face of the sun, which would still be interesting given that the sun has been very quiet for years. But what makes it even more extraordinary is that solar scientists predicted that this would happen, even when this point was on the other side of the sun!
Sunspots are regions on the surface of the Sun of intense magnetic force. Normally, huge packs of ionized gas (called plasma) within the Sun arise through the interior due to their heat, and when they reach the surface they cool and fall back. This is pretty much what also happens when you reheat a pot of soup (assumed it’s a liquid and not plasma).
But if the magnetic field embedded in that plasma becomes tangled when it reaches the surface, the package cools down but cannot sink again. It persists, and because it is cooler than the surrounding material it appears dark: a sunspot.
Furthermore, the Sun goes through cycles of magnetic activity, which manifests itself in a way as an increasing and decreasing number of sunspots over time. It goes from the minimum to the maximum and returns to the minimum within about 11 years. Cycle 24, the last one, ended last year and cycle 25 started in September 2019.
Some spots popped up on the Sun, but on November 23 a new one peeked out from the western edge of the Sun, rotating into view. It was already a decent size, which means it formed while on the opposite side of the Sun, which we can’t see from Earth.
But that doesn’t mean scientists have no idea what’s going on down there. In fact, they’re getting pretty good at predicting what’s going on on the opposite side of the sun. They knew this place was there long before we could actually see it.
This is because of a field called heliosismology. On Earth, seismic waves are sound waves (more technically acoustic waves) that travel across the Earth. By measuring them we can understand what the deep interior of the Earth is like (which is how we know there are layers like the core and the mantle down there).
Same with the sun. All the furious activity on the Sun’s surface and deep within it creates acoustic waves that travel around. As they do so, the surface of the Sun vibrates like a drum. By measuring those vibrations very carefully, scientists can now only tell what is happening inside the Sun, but also on the other side.
The magnetic fields that permeate the Sun interfere with these waves and therefore they too can affect what is seen. That’s how the scientists knew this place – called Active Region 12786 – was on its way. The signal first appeared on November 14, but was weak and not large enough to base any claims. But it grew quickly, and in just one day it was big enough to be considered a solid survey.
And sure enough, November 23 became visible when the Sun’s rotation of about a month slowly brought it into view from Earth.
The spot itself is about 40-50,000 kilometers in diameter. It is easily three times wider than Earth! If I threw the Earth in the spot, it wouldn’t even touch the sides.
To be clear, this type of prediction has been made many times in the past; just a couple of weeks later they predicted the active region 12781, which was also visible on the Sun after it was rotated. What makes this new interesting is that the Sun is so quiet that the signal from 12786 was very clear and that is an important point. We don’t usually see any that big until the new cycle begins. For now I wouldn’t read too much about it; the Sun is mercurial* and it can be difficult to know what is going on in a given cycle.
But this kind of thing is important to know. Magnetic fields on the Sun can get quite exuberant and store a large amount of energy. This can be released in huge explosions called solar flares and even larger ones called coronal ejections of mas. Both can cause real damage to satellites orbiting the Earth and cause widespread blackouts on the Earth’s surface (they can create huge flows of electricity below the surface, called geomagnetically induced currents, which places a lot of emphasis on generators and energy distribution).
Apparently I saw the AR 12781 commercials about a week ago, and another group (AR 12783) just the other day; I have a pair of solar binoculars designed specifically for looking at the sun. NOT never look at the Sun without proper help, especially using things like binoculars or telescopes unless you know what you are doing. And even then you have to be very very careful, unless frying the retina and boiling the vitreous humor in your eyes are not the desired results.
Instead, you can watch current observations of the Sun from NASA’s SOHO online, including the visible light image. Another good site is Solar Monitor, as well as current images from the Solar Dynamics Observatory.
And remember: the Sun may look familiar and friendly, but it’s actually a ball of nuclear-powered boiling plasma over a million kilometers in diameter, and its magnetic field can literally connect with ours for over 150 million kilometers. of distance. We rely on it for heat and light, but we really need to keep an eye on it in case it decides to throw a little more in our way.
*Lol! To have!
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