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How to find STEVE, the purple streak that looks like an aurora but isn’t -Se

A panorama photo taken in southern Alberta in March 2017 shows a green aurora sandwiched between two pink arcs known as the Steve Phenomenon. (Alan Dyer/VWPics/AP)

Scientists say there may be a better chance of finding Steve in the night sky if solar activity increases in the next few years

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She’s been chasing the northern lights for nearly a decade, so amateur photographer Donna Lach can easily recognize the green, red and purple curtains of the aurora borealis dancing across the sky. But one Sunday night in September 2015, while watching a relatively weak aurora, he saw something he didn’t recognize. A strange mauve light with “a green blob” appeared to the west of the aurora.

“It was this pink arc, and at some point, it extended above me,” said Lach, who is based in the Canadian community of Plumas, Manitoba. “I didn’t really know what it was.”

He was seeing something rarer than Aurora. It was Steve.

Steve is not an Aurora, but you can think of it as a shy, distant cousin. It looks like it could be part of the family, but it has its own distinct style. The phenomenon usually appears as a long, narrow purplish-white arc, sometimes accompanied by a structure that looks like a green picket fence. It is faint and narrow, and occurs at lower latitudes and higher altitudes than most auroras. It’s hard to guess. (Then there’s the name, which we’ll address shortly.)

Seeing STEVE could be a brutal matter of space physics. Lach has managed to photograph Steve more than 20 times since that first sighting in 2015 – possibly the most of anyone on record – and has probably seen even more ribbons of light. Many of the leading researchers in the field have never seen the phenomenon of light.

Citizen scientists like Lach, in addition to satellite data and sky cameras, have become important sources for researchers investigating STEVE — when it forms and how to recognize it. A citizen-science project, called Aurorasaurus, allows the public to report sightings and connects amateur photographers with scientists. Since STEVE’s official identification in 2018, researchers, photographers and citizen scientists have learned what makes STEVE special. (A note: In a previous job at NASA, the reporter worked part-time for Aurorasaurus and wrote news releases about the discovery, although he had not previously worked with any of the researchers mentioned in this piece.)

Solar activity is expected to increase in the next few years, the researchers say, so there may be a good chance for the public to spot STEVE. During an intense geomagnetic storm last week, at least three people took pictures of the phenomenon.

“Someone who doesn’t have a degree in it can still contribute to scientific research,” said Lach, who recently retired as the school’s administrative assistant and now runs a farm.

Naming a series of lights “Steve” might seem a bit random, and it is.

Around 2015, Lach and a handful of aurora chasers began sharing photos of strange, thin aurora-like structures running east to west. He and others posted about the strange mauve arc online and in Facebook groups and thought it might be a phenomenon known as a proton aurora, a type of aurora that is broad and diffuse and invisible to the naked eye, requiring a camera-like instrument. Look at it. But scientists rejected that identification because the phenomenon was apparently bright, narrow and structured.

In an effort to call it something other than a purple ribbon-y thing, Chris Ratzlaff, an aurora chaser and photographer based around Calgary, Alberta, suggests something a little different: “Steve.” He drew the name from the animated children’s film “Hedge over“which she recently watched with her children. In one scene, the animal characters are frightened by an unfamiliar pruned bush and decide to call it Steve.

As scientists began to look at satellite data and photos in more detail, they determined that this thin ribbon of light was actually a very fast stream of particles in the upper atmosphere that felt so hot that they ignited. Published by a team of space physicists and citizen scientists Primary studies Identifying Steve in 2018.

Scientists have given this phenomenon a backronym: strong thermal emission velocity increases.


Even if you haven’t seen Steve, his influence can be felt by Earthlings in other ways.

STEVE researcher Toshi Nishimura described at least one instance in which a radio signal from a radar network disappeared for 30 minutes when STEVE was displayed, but then returned after the ghostly light left the area, suggesting that the phenomenon could disrupt such signals. . Similar blackouts can occur with space weather associated with auroras, but he said STEVE occurs in different regions than an aurora and will affect different satellites and networks.

STEVE is important because Earth’s magnetic field is “doing something different than normal. … We still don’t understand why,” said Nishimura, who A study was recently published On to Steve’s mystery. He can still see the event in person.

How do you know if what you see is Steve?

STEVE has gained popularity in the past decade, but observations are believed to date back to the 1880s. Of course, it wasn’t known as Steve then. Photographs were also unavailable early on, so sightings were sometimes described through text or sketches.

A Research published in 1891, one observer described a “luminous band extending east and west” like the straight tail of a large comet. In 1933, aurora pioneer Carl Stormer took an early picture of the phenomenon A black and white photo.

A few weeks after STEVE was officially identified in 2018, citizen-scientist Michael Hunekuhl began digging through past studies and compiled a list of these historical and recent observations. He built a database of over 1,000 observations, which he said is probably the largest STEVE database in the world.

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

“Steve’s incidence rate and observation rate may be different, especially if you go back a few years, because people weren’t aware of Steve,” Hunekuhl said. Weather can also affect reporting rates, he said, because people may be less likely to go outside in certain conditions.

Nevertheless, several trends have been observed in the data: STEVE is most often seen near the equinoxes in March and September (this is when auroral activity typically increases). Visible pressure lasts about 30 minutes and rarely after midnight.

STEVE is seen together with an Aurora, although it is usually physically separate. It appears about 30 minutes after the aurora begins to brighten. Latch says he found Steve looking at the west end of Aurora. STEVE can be blocked by a bright aurora, though, especially if it’s close to it. Lach said he usually sees Steve when the aurora is weak or solar activity is relatively low.

STEVE can also take slightly different forms. It may appear as a small arc to the west of the aurora or may extend across the entire sky from east to west. Larger releases also show more depth of color — a deep red at the top, mauve in the middle, and white at the bottom.

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

How is Steve different from Aurora?

Steve and Aurora are both a ghostly light phenomenon in the atmosphere, but that’s where the similarity ends.

NASA researcher Bea Gallardo-Lacourt, who has been part of the STEVE study since the inaugural paper in 2018, points out a few differences in their creation: Auroras are a physical process, with electron and ion precipitation in our upper atmosphere and excited atoms. A star arc is a hot band of gas that involves a chemical reaction, producing an aurora in the ionosphere (more so than the aurora).

Gallardo-Lacourt, who had not even seen Steve, explained that the pressure is associated with a very fast flow of particles – about five times faster than seen in the aurora. one Recommended Procedure This powerful plasma flow excites nitrogen molecules in the atmosphere which interact with oxygen molecules, forming nitric oxide. This nitric oxide, which is otherwise rare in our atmosphere, is energized and illuminated, emitting light in the violet range of the visible light spectrum about 280 miles above Earth’s surface.

This NASA animation shows that STEVE (in purple) appears at lower latitudes than the North American aurora (in green). (Video: NASA GSFC/CIL/Krystofer Kim)

Their origins are also different. An aurora begins when the Sun sends a wave of energy to Earth, such as through an explosion on the Sun called a coronal mass ejection, and induces a large Geomagnetic storms. However, STEVE has occurred with and without geomagnetic storms.

Nishimura, a researcher at Boston University, said Steve always seems to occur during localized and brief disturbances in the Earth’s magnetic field, called substorms. Substorms can occur without a major geomagnetic storm and can occur daily. Yet despite the ubiquity of substorms, researchers are puzzled as to why sightings of Steve are still relatively rare compared to auroras.

With each photo and report, people are understanding more about this relatively unexplored part of our atmosphere and its connection to the Sun. If you have seen STEVE, contact any of the researchers — or Share your views with us on Twitter.



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