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Steve: Discover the phenomenon of lights that can be confused with auroras

Not all science is done by people in white coats under the fluorescent lights of academic buildings. Occasionally, the trajectory of the scientific record is forever altered inside a pub over a pint of beer. This is the case with the broad purple and green lights that can hover on the horizon in the Northern Hemisphere. The phenomenon looks like an aurora, but in fact it is something completely different and is called Steve .

The rare light show has caused a bit of a stir this year as the Sun is entering its most active periodincreasing the number of stunning natural phenomena appearing in the night sky – and leading to new reports of people spotting Steve in areas he doesn’t normally see, such as parts of the UK.

But about eight years ago, Elizabeth MacDonald, a space physicist at NASA’s Goddard Space Flight Center, was in Calgary, Alberta, for a seminar; she had never seen the phenomenon in person. And she still didn’t have a name. In fact, few scientists who actively study auroras and other night sky phenomena have witnessed a Steve, who looks more close to the equator than auroras and is characterized by a purple-pink arc accompanied by green vertical stripes.

After MacDonald gave a talk at a nearby university, she met with some citizen scientists – mostly photographers staying up all night hoping to capture the next stunning image of colors dancing in the Canadian sky – at the Kilkenny Irish Pub.

“I was already reaching out to local Alberta aurora hunters (in) a Facebook group, which was pretty small at the time,” said MacDonald, “but very interested in sharing their observations and interacting with NASA.” Photographers came with their photos in hand, eager to show off the mysterious light show they had captured.

The pinkish-purple band of light indicative of Steve is shown in this image captured by Canadian photographer Neil Zeller

Why “Steve”?

At the time, “we didn’t know exactly what it was,” MacDonald said of the phenomenon depicted in the images. Neil Zeller, a citizen scientist or photography expert — as aurora-hunting photographers are sometimes called — was at that meeting.

“I started detecting what we used to call a proton arc in 2015,” Zeller said. “It had been photographed in the past but incorrectly identified, and so when I attended that meeting in the Kilkenny Pub… we got into a little argument about (whether) I had seen a proton arc.”

“And the conclusion that night was, well, we don’t know what this is,” Zeller said. “But can we stop calling it the proton arc?”

It was shortly after that pub meeting that another aurora hunter, Chris Ratzlaff, suggested a name for the mysterious lights on the group’s Facebook page. Group members were working to better understand the phenomenon, but “I propose that until then we call him Steve,” Ratzlaff wrote in a February 2016 Facebook post.

The name was borrowed from “Over the Hedge,” the 2006 DreamWorks animated film in which a group of animals are startled by a huge leafy bush and decide to refer to it as Steve. (“I’m a lot less afraid of Steve,” declares a hedgehog.) The name stuck. Even later the phenomenon could be better explained. Even after the explanations for Steve began to take shape in scientific articles.

Scientists later developed an acronym to go with the name: Strong Thermal Emission Velocity Enhancement. And that meeting in a small Canadian pub was a turning point.

“That was the in-person meeting that was one of the pieces that provided the most impetus to eventually collect more and more observations in an increasingly rigorous way to where we could correlate that with our satellite,” MacDonald said.

What is “Steve”?

Eventually, MacDonald said a satellite directly observed Steve, collecting crucial data and leading to a 2018 study who suggested that the lights are a visual manifestation of something called subauroral ion drift, or SAID — which refers to a narrow stream of charged particles in Earth’s upper atmosphere.

Researchers already knew SAID existed, MacDonald said, but they didn’t know that it might occasionally be visible.

Steve is visually different from auroras, which are caused by electrically charged particles that glow when they interact with the atmosphere and appear as dancing ribbons of green, blue, or red. Steve – if it is caused by SAID – is made up of basically the same thing. But it appears at lower latitudes and appears as a band of lilac light accompanied by distinct green bands, often referred to as a picket fence.

Steve can be frustratingly difficult to spot, appearing alongside auroras with little regularity. Sometimes spotting Steve is a matter of luck, noted Donna Lach, a photographer based in the Canadian province of Manitoba.

A Steve will always appear alongside an aurora, Lach and Zeller said, but not all auroras include a Steve.

How and where to see a Steve?

Earth is entering a period of increased solar activity, which occurs every 11 years or so, MacDonald said. During this period, viewers can expect more light shows visible in the sky and – potentially – the opportunity to witness a Steve at low latitudes. Luminous phenomena have been detected as far south as Wyoming and Utah, she said.

Steve is best seen through the lens of a still camera or cell phone, however. To the naked eye, it may appear to be nothing more than a faint trail from a plane flying across the sky, Zeller and Lach noted, and it can be easy to ignore.

Zeller and Lach said they typically see Steve between midnight and midnight. “It’s not an all-night thing,” Zeller said. “The longest Steve has ever seen it was an hour from start to finish.”

MacDonald encourages anyone interested in photographing auroras – or Steve – to get involved with online communities. Aurorasaurus, a site which connects photographers with scientists, is a project she said she cares deeply about, noting its crucial role in helping scientists formally identify Steve.

Photos provided by the public constantly help scientists improve their understanding of these light shows, she said.

“Scientists are not as good aurora hunters as the passionate public,” she said. “We don’t stay up all night, nor are we photographers.”

Source: CNN Brasil

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