Why were the northern lights visible so far south?

WHAT is going on with the sun? Why were the northern lights visible as far south as Mexico?? Is the sun ok???

These are very good questions, and we’re going to dive into everything you might want to know about how the northern lights work, why they’re so difficult to predict, the sun’s solar cycle, and solar maximum.

The solar cycle and solar maximum

Let’s start with the sun’s solar cycle, because this all ties back to our host star. The sun is on an 11 year cycle, driven by its magnetic field. Every 11 years, the magnetic poles of the sun flip, and the months leading up to (and after) that flip are characterized by intense solar activity. Some solar cycles are more active than others. 

We’re currently in solar cycle 25, and it’s ramping up much faster than scientists initially predicted. While they first thought that solar maximum would arrive in mid-2025, it turns out that we’re basically IN or very near solar maximum now. Scientists also thought this would be a weak period of solar maximum, but that hasn’t been the case. As you can see, and this will be a theme in this newsletter, solar activity is difficult to predict. 

Scientists look forward to solar maximum because it’s a chance to study the weird inner workings of our sun, and we all look forward to solar maximum because — we get to see the aurora!!

The sun is busy fusing hydrogen into helium at its core — but a lot of the other inner workings of our sun are a mystery. What we do know is that the heat that this nuclear fusion generates creates extreme temperatures within our core. We think it’s around 27 million degrees F or 15 million degrees C.

That heat travels to the convection zone, which is above the sun’s core, and it turns superheated gas into plasma — which is basically gas that’s so hot that it carries an electrical charge. That plasma moves through the sun, sort of the way currents run through our ocean, and generates the magnetic field. This process is called the dynamo. Sunspots are the visible manifestation of the dynamo, the movement of the sun’s magnetic field.

Sunspots make all the magic happen

With all this magnetic field activity comes the rise of sunspots, We determine the sun’s 11-year solar cycle by how many sunspots it has; peak sunspot activity is when the sun is at solar maximum.

Sunspots are cooler, darker regions that are concentrations of the sun’s magnetic field on the star’s visible surface. When I say cool, I’m talking relatively — while the visible surface of the sun, the photosphere, is about 10,000 degrees F or 5,500 degrees C, sunspots are around 6,300 degrees F or 3,400 degrees C. 

In sunspot regions, the sun’s magnetic field is much stronger than anywhere else on the sun. We don’t exactly know why they form, but the prevailing theory is that the sun’s magnetic field is like a rubber band, and eventually it can become twisted and snap. When they do, these “snapped” areas rise to the surface as sunspots.

They can form over periods of a few days and last for months. Smaller sunspots can cluster together to form larger ones, and when that happens, there’s a ton of solar activity that can affect the Earth.

NOAA predicted that solar maximum would occur between January and October 2024, with a maximum number of sunspots between 137 and 173. As of the morning of May 13, there were 186 sunspots on the sun. In contrast, in 2019 when this solar cycle began, there were 274 days that went by without sunspots. (Solar minimum for this cycle was December 2019)

The beast io the left of the warning above is AR 3664, and it’s responsible for the bulk of the solar activity we saw over the weekend. This gargantuan sunspot is 17 times wider than the Earth, according to NOAA. It’s so big that when it was pointed straight at us, it was visible through solar viewers with the unaided eye — you didn’t even need solar binoculars. (Remember, don’t try to look at the sun without proper eye protection!)

Over the past 10 days, along with another sunspot called 3663, it’s sent out a flurry of solar flares and coronal mass ejections, which can cause the northern lights to appear.

Solar flares and coronal mass ejections: An explanation

Solar flares are basically giant explosions on the sun; we think they are tied to sunspots and they happen when sunspots release their energy. Solar material becomes heated to millions of degrees in just a few minutes and then it’s released in a burst of radiation. These can last minutes or hours, and we can usually see them at most wavelengths of light across the spectrum. 

Flares can send electromagnetic radiation hurtling through space, but most solar flares are pretty basic. These are called A and B class flares, and we don’t really see any impact to Earth from these. C-class flares come next, and then M-class. The highest categorization of solar flares is X-class flares — these are major events, and they’re often the trigger for CMEs or coronal mass ejections.

While solar flares do send radiation speeding towards Earth, CMEs are what people traditionally THINK of when they hear “solar flare.” These are bubbles of charged plasma and the sun’s magnetic field that are violently released into space. Remember, the sun’s plasma is gas that’s so superheated by the core it becomes charged. These energetic particles and magnetic field travel through the solar system, away from the sun, after they’re ejected.

They don’t travel at the speed of light (light takes about 8 minutes to travel from the sun to the Earth). When directed at the Earth, CMEs can hit us in as little as 15 to 18 hours, so we do have some advanced warning, but not much. They can travel anywhere from 250 km/s to 3,000 km/s or 155 mi/s to 1,860 mi/s

NASA has a really cool video of the journey of a CME, thanks to the Solar Dynamics Observatory which caught the CME in different wavelengths. The Stereo A and B spacecraft (which orbit the sun ahead and behind Earth) caught the CME with their coronagraph, which blocks out the sun so the spacecraft can image the sun’s upper atmosphere. This is traveling at 6.7 million miles per hour.

As the CME approaches the Stereo A spacecraft, notice the white across the screen (also pictured below)? That’s because the spacecraft is becoming overwhelmed by the CME’s charged particles.

You can see what the charged particles did to Stereo A. When they impact the Earth’s atmosphere? That’s what creates the northern and southern lights.

What causes the northern lights?

And this is what makes the northern lights so difficult to predict. I know a lot of people were upset that they missed the show Friday night because they didn’t hear in advance it was happening. We didn’t know it was going to happen, and NOAA’s prediction was not for an aurora so strong it could be seen from Florida, Texas, and Mexico.

It was a wonderful surprise, but unlike the eclipse, we can’t really tell you much about when or where northern lights are going to happen in advance.

The aurora, are the result of these charged particles from solar activity slamming into the Earth’s atmosphere at 45 million mph/72 million kph. They become entangled in our magnetic field and accelerate to the poles of our planet. They interact with the particles in our own atmosphere, heating them up, and that’s what causes the aurora. 

If you did see the aurora over the weekend in an area that doesn’t normally get it, you may have noticed it appeared colorless, with the color only coming out through a camera. I got a lot of questions about whether this is how the aurora always appear, and the answer is — yes and no.

When you’re in a place where the aurora is weak — which, if you’re in Missouri or Florida and looking at the northern lights, it’s going to be weak — it does appear colorless to the unaided eye. But that’s not always the case, when I was in Iceland and saw them for example, they had definition and color and were moving around to the unaided eye.

The colors do have significance. The traditional green is due to oxygen in the Earth’s lower atmosphere, it’s about 80 miles/128 km up. Hints of blue, purple, and pink are the result of nitrogen. However, a lot of people just saw a red, without much definition — that is the result of oxygen in the Earth’s upper atmosphere, and it’s not a common phenomena.

If you’re wondering will this happen again — it’s possible. The gargantuan sunspot 3664 has rotated away from us, but that doesn’t mean a new one won’t form soon.

As I mentioned, we’re not done with solar maximum yet, and according to an article in Nature some of the biggest solar activity can happen AFTER solar maximum — so it’s very possible this is just the beginning. 

Are we in any danger from solar storms?

So now let’s turn to: Given this heightened solar activity, are we in any danger? The answer, not, but there can be real consequences for events like this.

Let’s talk about the Carrington Event which was the most powerful solar storm on record. It took place in September of 1859, and a sunspot that was similarly sized to our own 3664 released a massive solar storm (a flare and CME). About 18 hours later, it hit the Earth. The northern lights were visible in the tropics thanks to the ensuing geomagnetic storm.

So what would happen if an event similar to the Carrington Event occurred today? Well, the internet could go down across the planet. There would be major disruptions in the power grids, satellites might fall out of the sky, GPS would go haywire — it’d be a big deal. 

This particular solar storm that we just had was powerful. There were some localized blackouts and GPS was a mess. While as far as we know no satellites fell out of the sky, SpaceX’s Starlink had “degraded service” due to disruptions because of the geomagnetic storm.

If you’re worried about astronauts, who aren’t as protected by the Earth’s atmosphere as we are, well, there is a plan for that. While NASA said that the astronauts didn’t need to take precautions during this event, generally they can take shelter in the Zvezda module, which provides the best protection during solar storms because of its location furthest from the sun. 

These kinds of storms are also a concern for space travel to the moon, Mars, and beyond, which is part of the reason we’re doing so much work in studying how radiation affects astronauts and what we can do to protect them.

No the northern lights weren’t artificially created

Because I love ending things on a weird note: There is a conspiracy theory about the northern lights. You probably saw reference to it if you were looking at posts about it this past weekend.

According to this theory, these people seem to think that an organization called “HAARP” artificially created the northern lights. I don’t need to tell you that isn’t the case.

To be clear, HAARP is a real program. It’s the High-Frequency Active Auroral Program out of the University of Alaska, Fairbanks. It focuses on studying the ionosphere, and it sometimes can heat small areas of it and observe effects. 

HAARP conspiracy theories are abundant for some reason. People say they can do everything from controlling the weather to mind control to chemtrails (literally the official HAARP FAQ on the website says that no, HAARP can’t control the weather or do mind control).

In this case, people are saying HAARP created the aurora borealis over the bulk of the North American continent. It cannot, in fact, do this. The program HAS created artificial aurora before, but in small areas of Alaska, but people are fired up because apparently there was a HAARP experiment going on May 8-10 (to be clear I haven’t been able to independently confirm this, and I didn’t really want to go wading through the sites that had this posted).

But in case you were following stories about the northern lights, I wanted to flag that this may be something you will run into and to just keep in moving if you come across it.