Unraveling the Enigmatic Aurora ‘STEVE’: Triangulating its Origins and Earthly Connections

Unraveling the Enigmatic Aurora ‘STEVE’: Triangulating its Origins and Earthly Connections (Humanized Version)

We’ve all been mesmerized by the Northern and Southern Lights, right? The aurora borealis and australis, those shimmering curtains of green, pink, and violet that dance across the polar skies. But lately, there’s been a new kid on the block, a celestial oddity that’s got scientists and skywatchers alike scratching their heads: STEVE.

STEVE, which stands for Strong Thermal Emission Velocity Enhancement (try saying that five times fast!), isn’t your run-of-the-mill aurora. It’s this ribbon of purplish light that sometimes shows up further south than you’d expect, and it acts… well, different. And sometimes, just to make things even weirder, it brings along these green, vertical streaks that folks have nicknamed the “picket fence.” Cute, huh?

A Serendipitous Discovery: Thank You, Citizen Scientists!

The story of how STEVE was discovered is seriously cool. It’s all thanks to a bunch of amateur aurora enthusiasts, the Alberta Aurora Chasers. These folks were snapping photos of the night sky, sharing them on Facebook, when they started noticing this strange purple streak. They were like, “Hey, what is that?”

So, they did what any good citizen scientist would do: they reached out to the experts, Elizabeth MacDonald at NASA and Eric Donovan at the University of Calgary. Initially, they just called it “Steve” – a nod to the movie “Over the Hedge.” But the name stuck, and scientists later came up with that fancy backronym. Pretty neat how that works, isn’t it?

STEVE vs. Aurora: What’s the Diff?

Okay, so STEVE looks like an aurora, but it’s not really an aurora. Think of it like this: they’re cousins, but they have very different personalities. Auroras are usually green, blue, and red, and they can hang around for hours, putting on a real show. STEVE, on the other hand, is mostly purple, sticks around for maybe 20 minutes to an hour, and is caused by something completely different.

While auroras are created when charged particles from space crash into our atmosphere, STEVE is linked to this super-fast stream of hot particles called a sub-auroral ion drift, or SAID. Imagine a ribbon of plasma, hotter than lava (around 3,000 °C!), zipping along at 6 kilometers per second. That’s STEVE’s engine right there.

And here’s another thing: STEVE likes to hang out closer to the equator than auroras usually do. This is probably why scientists missed it for so long – there just aren’t as many cameras pointed at that part of the sky.

Pinpointing STEVE’s Location: It Takes a Village (and Some Satellites)

Figuring out where STEVE is and where it comes from has been a real detective story. Researchers have had to rely on those citizen scientists’ photos, plus data from satellites, to piece it all together. By comparing photos taken from different locations, they’ve been able to use triangulation to figure out how high up STEVE is.

One study even used photos taken by two amateur photographers who were 400 km apart! Talk about teamwork! That research showed that the purple and green parts of STEVE are at different altitudes but connected by the same magnetic field lines. That means they’re both powered by the same region of the magnetosphere, way, way up there – like 30,000 km above Earth. Pretty wild, huh? And in 2022, they found the purple part of STEVE sits stable at 150-170 km high, while that green picket fence is steady at 110 km.

But just when you think you’ve got it all figured out, nature throws you a curveball. A 2024 study found a STEVE event that happened without a substorm, which is usually part of the STEVE recipe. So, yeah, we’re still learning!

The Picket Fence and Other Earthly Connections

And what about that “picket fence,” those green stripes that sometimes come along for the ride? At first, scientists thought they were just regular auroras, but it turns out they’re something else entirely. The current thinking is that they’re caused by showers of electrons from space, kind of like auroras, but happening in a different way because of some “special” conditions in the atmosphere. Some scientists even think it could be turbulence in those charged particles. Who knows?

What’s also interesting is that there’s some evidence that STEVE can pop out of SAR arcs, which are another type of glowing light in the sky. SAR arcs happen when the magnetosphere gets disturbed, and that disturbance heats up the ionosphere. It’s all connected, somehow.

The Adventure Continues…

Even though we’ve learned a ton about STEVE in the last few years, there are still plenty of mysteries to solve. What exactly makes that purple light? How do STEVE, SAIDs, and the picket fence all fit together? And is STEVE even a real aurora, or something else entirely? Some new research suggests it’s actually caused by electric fields that run parallel to Earth’s magnetic field. Mind. Blown.

The discovery of a STEVE “twin” on the other side of the sky has just made things even more interesting. If STEVE has a counterpart, that could give us some serious clues about how it works.

STEVE is a great example of how science works: it’s a puzzle, and we’re all working together to solve it. And it shows that even in this day and age, the night sky can still surprise us. With citizen scientists, cutting-edge technology, and a healthy dose of curiosity, we’re sure to unlock even more of STEVE’s secrets in the years to come. It’s going to be one heck of a ride!