Reader Response: Space Weather

We got a question from a reader on our Spacing Out newsletter survey asking about the importance of space weather. I’m very excited this question got asked, because it means I’ll get a chance to discuss something I bring up frequently in the newsletter, in the Planetarium, and to random people on the street if they’ll hold still long enough, because it’s cool and relevant: Solar Cycle 25.

Buckle up buttercups, we’re going Sun diving!

Space Weather

For those unfamiliar with the term, the idea of space weather might seem a strange one. There’s no weather in space, after all, at least not what we here on Earth are used to thinking of as weather. But there are changing conditions in our solar system that can have effects on the planets, and these conditions come from the only thing within our solar system big and powerful enough to affect the entire thing: the Sun.

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Our local star is a healthy, active, middle-aged creature, which means its insides and its surface are absolutely roiling with activity 

 (side note: “roiling” is a great word and should be used more often). One of the ways this activity visibly manifests on the Sun’s surface is in the form of sunspots, darker patches on the Sun. 

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 These areas appear dark because they are actually cooler than the surface around them (cooler being a relative term—it is still the surface of the Sun). They are formed when the Sun’s magnetic field, which is a whole ridiculously tangled spaghetti pile of magnetic field lines, gets particularly twisted up and goes through the surface of the Sun.

One way of measuring just how frisky our star is feeling at any particular moment is by counting the number of sunspots. When the Sun is going through a quiet period it will have few or even no sunspots. When it’s more worked up, the Sun’s surface can be peppered with sunspot groups. Keeping track of sunspots is important because they are what give rise to the “storms” of space weather: solar flares and coronal mass ejections.

Sometimes the twisted up magnetic field lines that form a sunspot group get so contorted and tangled that they actually snap. This is the source of solar flares, and it releases a whole lot of energy and radiation into space. Essentially they’re like explosions on the surface of the Sun. They can be small or they can be incredibly large. They are sometimes accompanied by huge masses of plasma from the Sun’s outer atmosphere, known as the corona. When this happens we call it a coronal mass ejection, or CME. They’re incredible to see, in the same way watching a building get demolished is incredible to see—excessively cool with just a touch of alarm from the lizard hindbrain for spice. 

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Both of these kinds of events, flares and CMEs throw a lot of energy and charged particles out into space. This is what we usually mean when we refer to space weather—all that stuff coming off of the Sun in various directions and becoming the rest of the solar system’s problem.

How Much Should the Average Earthling Care?

You’re reading a space blog, so I’m going to assume you care about space weather purely because it’s cool. But suppose you were one of those poor, deprived souls who don’t understand that space is, in fact, the most amazing thing there is and doesn’t want to know more about it just for the sake of having more cool stuff in their life. Should that person care about space weather?

On a normal day-to-day basis: not really. Space weather is going to affect your daily life a whole lot less than regular old terrestrial weather will. But if we weren’t prepared for it, space weather could lead to everyone have a Very Bad Day. Followed by a Very Bad Several Years, most likely.

For the most part Earth’s magnetic field protects us from the stuff streaming off the Sun. There’s actually a fairly constant stream of particles that we call the solar wind just pouring off of our star, and we don’t even really notice because Earth’s magnetic field shields us. 

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 When a good-sized flare or CME is pointed towards the Earth, we might notice a little. All those extra charged particles pouring into Earth’s magnetic field can lead to radio blackouts, and it’s what causes the Northern and Southern Lights.

But sometimes the Sun throws a major tantrum, and erupts in a very powerful flare. These are the ones we have to watch for, because a really strong flare directed at Earth would mean Very Bad Things for our satellites and our electrical grids (among other things). And, of course, our modern civilization depends on things like satellites and electrical grids to, you know, exist. A bad enough flare hitting Earth and catching us by surprise could lead to critically damaged, crippled power systems all over the world. And once these systems go down, it would take a long time to fix them all.

It’s happened before in more minor ways. In 1859 the Sun let out a frenzy in Earth’s direction that is known as the Carrington Event. There weren’t a lot of electrical systems around in 1859, but there were telegraph networks. The current induced in the telegraph wires by the charged particles streaming down from the Sun set telegraph offices on fire. Such an event today would really mess things up. In 1989 a power network in Quebec was brought down by a solar storm. In this case the damage was relatively minor and fixed quickly.

Knowing these storms are heading our way can allow us to take some mitigating measures, such as powering off electrical grids temporarily. These measures may not be able to stop all damage from a sufficiently strong solar event, but it can moderate the effects. This is why we have spacecraft with one job and one job only: stare at the Sun. Ground-based facilities such as the Daniel K. Inouye Solar Telescope are limited by the fact that Earth rotates (usually considered a good thing) and they spend part of the day in darkness. But space-based observatories such as the Solar Dynamics Observatory or the Solar and Heliospheric Observatory don’t have that problem. They can stare at the Sun 24 hours a day every day.

Solar Cycle 25

This brings me back to Solar Cycle 25. Our Sun goes through an 11-year cycle of activity that we call the solar cycle. During this 11 year period the Sun generally starts at a period of low activity, called solar minimum, ramps up to a period of high activity called solar maximum, and then calms back down to a minimum, at which point that cycle ends and the next one is considered to have begun. Tracking of these cycles began in 1755 and we are currently in the 25^th such cycle since tracking began.

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Solar Cycle 25 started in December 2019 (if you weren’t paying any attention to astronomy stories about the start of the new solar cycle in the first several months of 2020 it might be because there were other things to pay attention to at that time). It was preceded by a rather pathetic showing in Solar Cycle 24, which didn’t have much in the way of a solar maximum. 

Early predictions had Solar Cycle 25 following the same pattern, with a relatively quiet solar maximum. Of course the Sun respects our expectations for its behavior about as much as a cat would, which means not at all, and thus far Solar Cycle 25 has been quite active. The Sun was well ahead of predictions for number of sunspots for June, the last complete month of the solar cycle, and if you’ve been hearing increased aurora alerts recently, that’s because the Sun is a-flaring on the regular now. 

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There’s even been one truly enormous event that erupted from the Sun in March that would have been a capital-P Problem if it had been aimed at Earth. This event was as strong, or possibly stronger, than the Carrington Event. Fortunately for us, the Sun did us the very great favor of spewing this huge storm out on the exact opposite side from Earth. It was powerful enough that it had minor effects on Earth anyway, but nothing big. At least some scientists suspect that this will be the strongest blowout of Solar Cycle 25…but of course we know how predicting the Sun can be. It is currently suspected that Solar Cycle 25 will peak in mid-2025 (appropriately enough), but the level of activity we’re seeing makes some astronomers wonder if the Sun might peak a bit early.

What Was the Question Again?

I got excited and lost track, but the original question was how important space weather is. And hopefully I’ve shown well enough that the answer is not-very if you’re lying in bed thinking about how space weather is likely to affect your commute on any given day, and really-very if your civilization relies on electricity and wants to keep doing so.

Our star is a temperamental beast and its power must be respected. That power makes life on Earth possible but it could also cause huge problems for our modern society if we’re not paying attention. Fortunately we are paying attention and our Sun is always being monitored. As we head towards the peak of Solar Cycle 25 with all of its sunspots and solar storms, while we do still need to watch out for major events we can also gloat that we live on a world with a strong magnetic field as we sit pretty behind Earth’s invisible shield enjoying all the extra chances for aurora watching.

After all, if you want to see what happens without a magnetic field, just look at Mars.