STEVE is the new kid on the block now that the Aurora Borealis is making its way out

Steve Rogers has left the building and STEVE has entered. The Aurora Borealis or the Northern lights has always captured the attention of people and photographers all over the world. With recent reports of the Borealis dying off, STEVE might take over. Bonus: it does not only occur in the auroral zones. They usually occur in populated/residential areas.

What is Aurora Borealis?

Aurorae are caused by charged particles hitting atoms and molecules in Earth’s atmosphere, causing them to glow. Traditional aurorae are often green because oxygen atoms present in Earth’s atmosphere emit that colour when they’re bombarded by charged particles trapped in Earth’s magnetic field. They also appear in a diffused glow — rather than a distinct line — on the northern or southern horizon according to the report in Science. [caption id=“attachment_6581031” align=“alignnone” width=“1280”] The Aurora Borealis. image credit: Good Free Picture[/caption]

What is STEVE?

STEVE stands for Strong Thermal Emission Velocity Enhancement. It is similar to the Aurora Borealis but unlike the Aurora, it is mostly mauve and purple. It is a band of light, stretching east to west that appears across the sky. It sometimes also has a second arc of green which is also known as a picket fence. It appears in much lower latitudes.

How did it get its name?

A group of citizen-scientists led by Chris Ratzlaff from Alberta, Canada named it STEVE, after a line in the 2006 children’s movie Over the Hedge. [caption id=“attachment_6581061” align=“alignnone” width=“1280”] STEVE (Strong Thermal Emission Velocity Enhancement) and the Milky Way at Childs Lake, Manitoba, Canada. The picture is a composite of 11 images stitched together. Image Courtesy: Krista Trinder/Flickr [/caption]

How does it occur?

Elizabeth MacDonald, a space physicist at the NASA Goddard Space Flight Center in Greenbelt, Maryland, and her team have used data from a European satellite called Swarm-A to study STEVE and has published the findings in the journal Science Advances. Appearing about 200 kilometres up in the atmosphere the satellite revealed that the charged particles had a temperature of 6,000 degree Celsius. These ions flow east to west at nearly six kilometres per second, propelled by electric and magnetic fields in the atmosphere. The heat and motion contribute to the purple hue. What causes the purple hue is still unknown.

What is the picket fence?

The picket fence is the secondary light arc that appears along with STEVE. It is caused by a similar process to what causes auroras, although it is closer to the equator than where the auroras are seen. They are caused by energetic electrons streaming into Earth’s atmosphere from thousands of kilometres away and occur in both Northern and Southern hemispheres simultaneously. These arcs have been occurring and have been observed by aurora chasers before scientists got the wind of it. Hence, it is only now that scientists are studying it.