April 17, 2024

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How to find STEVE, the purple line that looks like the Northern Lights but isn’t

A panoramic image taken in March 2017 in southern Alberta shows a green aurora surrounded by pink arcs known as the STEVE phenomenon. (Alan Dyer/VWPics/AP)

Scientists say there may be good chances of detecting STEVE in the night sky as solar activity increases over the next few years


They’ve been chasing the northern lights for nearly a decade, so amateur photographer Donna Lash can easily identify the green, red, and violet curtains of light of the Northern Lights dancing across the sky. But one Sunday night in September 2015, while watching a faint aurora borealis, she saw something she didn’t recognize. A strange violet light accompanied by a “green dot” appeared to the west of the aurora borealis.

“It was this pink bow, and at one point it stretched out over me,” said Lash, a resident of the Canadian community in Plumas, Manitoba. “I didn’t really know what it was.”

She was seeing something rarer than the Northern Lights. Steve was.

Steve is no Northern Lights, but you can think of him as his shy, distant cousin. It looks like it could be part of the family, but it has its own distinct style. The phenomenon generally appears as a long, slender arc of violet and white colour, sometimes accompanied by a green picket fence-like structure. It is lighter and narrower, and occurs at lower latitudes and higher altitudes than most aurora borealis. It is also difficult to predict. (And then there’s the name, which we’ll get to shortly.)

Steve’s vision could be a matter of chance in space physics. Lach has shot STEVE more than 20 times since that first sighting in 2015 — likely more than anyone on record — and may have seen the light bar more than that. Many of the leading researchers in this field have not even seen the phenomenon of light once.

Citizen scientists like Lach, along with satellite data and sky cameras, have been vital resources for researchers looking at STEVE — when it forms and how to identify it. One citizen science project, called Northern lightsIt allows the public to report sightings and connects amateur photographers with scientists. Since STEVE’s official definition in 2018, researchers, photographers, and citizen scientists have learned what makes STEVE special. (Note: In a previous job at NASA, the reporter worked part-time on Aurorasaurus and wrote news releases related to the discovery, though she had not previously worked with any of the researchers mentioned in this article.)

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Solar activity is expected to pick up over the next few years, the researchers say, so there may be good chances for the public to spot STEVE. During a severe geomagnetic storm last week, at least three people filmed the phenomenon.

“A person without a degree in it can still contribute to scientific study,” said Lash, who recently retired as the school’s administrative assistant and now runs a farm.

Naming a line of light “Steve” might seem a bit random, and it is.

Around 2015, Lash and a few other Aurora stalkers began sharing images of the strange, thin structure that resembled the Northern Lights stretching from east to west. She and others also posted about the strange violet arc online and in Facebook groups and thought it might be a well-known phenomenon called proton aurora, a type of aurora that is widespread and invisible to the naked eye, and requires tools like a camera to see it. But scientists have refuted this identification because this phenomenon was visually bright, narrow and orderly.

In an effort to call it something besides a purple ribbon, Chris Ratzlaff, aurora stalker and photographer around Calgary, Alberta, suggested something a little different: “Steve”. The name was extracted from the children’s animated film “On the edge, which he recently watched with his children. In one scene, the animal characters are frightened by an unfamiliar manicured bush and decide to name it Steve.

When scientists began to look at the satellite data and images in more detail, they determined that this thin band of light was actually a very fast stream of particles in the upper atmosphere getting so hot they glow. A team of space physicists and citizen scientists published Preliminary study Steve’s fix in 2018.

Scientists have given the phenomenon a back name: the velocity boost of strong heat emission.

What are some of Steve’s influences?

Even if you haven’t seen Steve, Earthlings may suffer its effects in other ways.

STEVE University researcher Toshi Nishimura recounted at least one case in which a radio signal disappeared from a radar network for 30 minutes as STEVE appeared, but returned once the ghostly light left the area, suggesting that this phenomenon could disrupt such signals. Similar blackouts can occur with space weather associated with the aurora borealis, but he said STEVE occurs in different regions than the aurora borealis and will affect different satellites and networks.

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STEVE is important because Earth’s magnetic field “does something different than usual. We still don’t understand why,” said Nishimura, of recently published a study About Steve secrets. He had not personally seen this phenomenon yet.

How do you know if what you’re seeing is Steve?

STEVE has gained a lot of popularity in the past decade, but the notes are believed to date back to the 1880s. Of course, he wasn’t known as STEVE at the time. Pictures were also not available early on, so scenes were sometimes described through text or sketches.

in The study was published in 1891One observer described a “luminous band stretching east and west,” like the straight tail of a large comet. In 1933, an early photograph of the event was taken by Northern Lights pioneer Carl Stürmer Black and white photo.

Just weeks after STEVE was officially identified in 2018, citizen and scientist Michael Honkull began digging through past studies and compiling a list of these historical and recent observations. He created a database of more than 1,000 notes, which he says is probably the largest STEVE database in the world.

STEVE has been observed on every continent, including Antarctica. The highest number of reports come from Canada, Finland and parts of the United States, although this may be a result of higher awareness of the phenomenon in those locations.

“The incidence of Steve and the rate of observation can vary, especially if you go back a few years, because people weren’t aware of Steve,” Honcol said. He said the weather may also affect reporting rates, because people may be less likely to go outside in certain circumstances.

However, several trends emerged in the data: STEVE appears most often in March and September near the equinoxes (which is also when aurora activity usually increases). The visible arc lasts about 30 minutes and very rarely after midnight.

STEVE is seen in conjunction with the Northern Lights, although it is usually physically separated. It appears about 30 minutes after the aurora borealis begin to brighten. Lash said she found Steve by looking out from the western edge of the Northern Lights. However, STEVE can be obscured by a bright aurora, especially if it is close to it. Lash said she usually sees Steve when the aurora borealis are faint or solar activity is relatively low.

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STEVE can also take on slightly different forms. It can appear as a short arc to the west of the aurora borealis or stretch across the entire sky from east to west. Larger appearances also show more depth in color – dark red above, violet in the middle and white below.

As the STEVE arc continues, a green picket fence may appear. Sometimes the arch disappears and the green picket fence remains.

How is Steve different from Twilight?

Both STEVE and the aurora borealis are ghostly atmospheric light phenomena, but that’s where the similarities end.

NASA researcher Pia Gallardo-Lacour, who has been part of STEVE’s research since the editorial paper in 2018, outlines some of the differences in their creation: Auroras involve physical mechanism, with electrons and ions raining down in the upper atmosphere and exciting atoms. A STEVE arc is a hot band of gas that involves a chemical reaction that results in a glow in the ionosphere (above the aurora borealis).

Gallardo-Lacourt, who also hasn’t seen STEVE, explains that the arc is associated with a very fast stream of particles — five times faster than seen in the aurora borealis. One proposed mechanism is that this powerful plasma flow excites nitrogen molecules in the atmosphere which then react with oxygen molecules, creating nitric oxide. This nitric oxide, which is rare in our atmosphere, is activated and glows, emitting light in the purple range of the visible light spectrum 280 miles above Earth’s surface.

This NASA animation shows STEVE (in purple) appearing at lower latitudes than the aurora borealis (in green) over North America. (Video: NASA GSFC/CIL/Krystofer Kim)

Their sources also differ. The formation of the aurora borealis begins when the Sun sends a burst of energy to the Earth, for example through an explosion in the Sun called a coronal mass ejection, and triggers a large-scale Geomagnetic storm. However, STEVE has occurred with and without geomagnetic storms.

Nishimura, a researcher at Boston University, said STEVE always seems to occur during short, localized disturbances in Earth’s magnetic field, called substorms. Substorms can occur without a major geomagnetic storm and occur daily. However, despite the ubiquitousness of substorms, researchers are at a loss as to why STEVE sightings remain relatively rare compared to the Northern Lights.

With each image and report, people understand more about this relatively unexplored part of our atmosphere, and its relationship to the sun. IF YOU SEE STEVE, CONTACT ANY OF THE SEARCHERS – OR Share your view with us on Twitter.