Stargazers in Scotland were treated to a glimpse of a mysterious aurora over the weekend that is so rare it was only formally identified by scientists last week.
The incredible phenomenon, dubbed ‘Steve’ was spotted during displays of the Aurora Borealis during the night.
The rare sight – which has baffled scientists for years – can be identified by its narrow arc that stretches for several hundred miles and has a distinctive purple hue.
First spotted by amateur astronomers as part of a 2015 citizen science project in Canada, the stunning display of dancing lights stumped scientists for more than two years.
‘Steve’ was spotted during displays of the Aurora Borealis during the night over Northern Scotland (pictured). The rare sight – which has baffled scientists for years – can be identified by its narrow arc that stretches for several hundred miles and has a distinctive purple hue (left)
Originally dubbed Steve, in honour of a hedge in the 2006 film Over The Hedge, experts allowed the phenomenon to keep its name, but also created a ‘backronym’, or backward acronym, to explain it – Strong Thermal Emission Velocity Enhancement.
On Sunday night, the unique visual display was seen over the isles of Skye and Lewis. It was also visible in Argyll and Gairloch in Wester Ross.
The Aurora Borealis (Northern lights) also appeared without Steve in many parts of Scotland.
Steve is created by a process more formally known as a subauroral ion drift (Said), although these are normally invisible.
Nasa has also asked members of the public to help track and understand the phenomena.
They have asked people to send in images and footage of Steve to the Aurorasaurus project to help further understand Steve.
Steve is created by a process more formally known as a subauroral ion drift (Said), although these are normally invisible. Pictured is the purple hue to the left of this photograph
Nasa has also asked members of the public to help track and understand the phenomena. The distinct purple of Steve can be seen alongside the green tones caused by the Aurora Borealis
HOW CAN YOU SPOT STEVE?
Steve was first observed over Alberta in Canada in 2015-2016 as part of a citizen science project.
Unlike most auroras, it appears closer to the equator.
It can be seen roughly 5-10 degrees farther south in the Northern Hemisphere than most auroras, such as the Northern Lights, can be seen.
This means it could appear overhead at latitudes similar to Calgary, Canada.
The phenomenon has been reported from the United Kingdom, Canada, Alaska, northern U.S. states and New Zealand.
Steve is a very narrow arc, aligned east-west, and extends for hundreds or thousands of miles.
Steve is predominantly purple streaks standing nearly vertically in the sky, with flashes of green that moved westwards.
Steve has only been spotted so far in the presence of an aurora (but auroras often occur without Steve).
In order to classify what Steve was properly, a team of researchers, including Elizabeth MacDonald from Nasa’s Goddard Space Flight Centre in Maryland, used the European Space Agency’s (ESA) Swarm constellation.
This is made up of three satellites with magnometers, which directly measure the movement of highly charged particles.
This allowed the team to directly measure ion flow velocity as well as ion and electron temperatures in the structure.
The data suggested the presence of a Said. Steve is the first visual effect to be detected that results from the phenomenon.
Nasa has also asked members of the public to help track and understand the phenomena (pictured in Scotland). They have asked people to send in images and footage of Steve to the Aurorasaurus project to help further understand Steve
Steve appears on wavelengths different from most auroras, which dedicated scientific cameras may routinely miss.
Improvements in the technology of cameras commonly used by the public mean records of such phenomena are growing, providing scientists’ valuable opportunities to better understand auroras.
Roger Haagmans of the ESA said: ‘It is amazing how a beautiful natural phenomenon, seen by observant citizens, can trigger scientists’ curiosity.
‘It turns out that Steve is actually remarkably common, but we hadn’t noticed it before.
‘It’s thanks to ground-based observations, satellites, today’s explosion of access to data and an army of citizen scientists joining forces to document it.’
Researchers first became aware of Steve after coming across pictures posted by members of a Facebook group called the Alberta Aurora Chasers.
Steve appears on wavelengths different from most auroras, which dedicated scientific cameras may routinely miss. Confusion as to its classification comes from the fact most similar auroras to Steve are invisible
Steve is an aurora that can be seen on the left of this image here. The rest of the milky way can also be seen in the crystal clear skies above Canada. Steve was unclassified by experts and bemused scientists for two years
Steve was first spotted by amateur astronomers as part of a citizen science project in 2015 but left researchers stumped. Now, Steve has finally been classified and has managed to keep its unique name
When classification became tricky and experts failed to name the aurora, the amateur astronomers took matters into their own hands. The group called it Steve in homage to a 2006 children’s film, Over the Hedge
They shared images of predominantly purple streaks standing nearly vertically in the sky, with flashes of green that moved westwards.
Eric Donovan from the University of Calgary in Canada was the first academic to come across Steve online and shared the images with his colleagues.
They realised that it was created by Saids, rare and poorly understood middle and low-latitude auroras.
Identification of the displays has proved difficult in the past and experts have dubbed the unusual, temporary and dim subauroral arcs they produce ‘proton arcs.’
However, Steve’s particular arc was bright, narrow, structured and at a lower latitude than typical proton arcs.
Steve is extremely common in the region, it turns out. Despite its frequency, the aurora had never been known to scientists. Amateur astronomers alerted scientists to the existence of the purple-green aurora
To classify Steve, researchers used the European Space Agency’s (ESA) Swarm constellation. Three satellites with magnometers that directly measure the movement of highly charged particles
Up to six localised structures could be seen at any one time and the authors say it ‘resembled a picket fence’.
Dr Donovan did not recognise it as a catalogued phenomenon and although the group were calling it a proton arc, he knew proton auroras were not visible.
Analysis at the time found that the temperature of the air was 3,000°C (5,432°F) hotter inside the gas stream than outside it.
Inside, the 25km (15 mile) wide ribbon of gas was flowing at 6 km/s (13,000mph), 600 times faster than the air on either side.
The full findings of the original study were published in the journal Science Advances.
Now, experts have determined it is a SAID (subauroral ion drift). Although these are normally invisible, Steve is unique and colourful
WHAT ARE THE AURORAS AND WHAT TRIGGERS THE STUNNING NATURAL DISPLAYS?
The Northern and Southern Lights are natural light spectacles triggered in our atmosphere that are also known as the ‘Auroras’.
There are two types of Aurora – Aurora Borealis, which means ‘dawn of the north’, and Aurora Australis, ‘dawn of the south.’
The displays light up when electrically charged particles from the sun enter the Earth’s atmosphere.
There are two types of Aurora – Aurora Borealis (file photo), which means ‘dawn of the north’, and Aurora Australis, ‘dawn of the south.’ The displays light up when electrically charged particles from the sun enter the Earth’s atmosphere
Usually the particles, sometimes referred to as a solar storm, are deflected by Earth’s magnetic field.
But during stronger storms they enter the atmosphere and collide with gas particles, including hydrogen and helium.
These collisions emit light. Auroral displays appear in many colours although pale green and pink are common.