NEW DELHI: With solar activity reaching levels not seen in over a decade, people residing in the northern and southern latitudes are frequently experiencing enhanced displays of the captivating northern and southern lights, commonly referred to as aurorae.

While aurorae have been well documented, the increased solar activity is proving an opportunity to astronomers to study a rarely seen light display that has become more visible, and its called Steve.What is Steve?While aurorae are predominantly seen in high-latitude regions and display dynamic patterns of brilliant lights that appear as curtains, rays, spirals, or dynamic flickers covering the entire sky, Steve can be seen further south than aurorae and sometimes appear as a purple and green light ribbon in the sky.While auroras happen globally in an oval shape, Steve appears as a ribbon and lasts for 20 minutes to an hour before disappearing.Sometimes, Steve even has a "picket fence" appearance, with green columns of light passing through the ribbon.

Little is known about its formation and why it can sometimes appear during an aurora display.As Steve is unpredictable and only lasts for a short time, recording occurrences from the ground is rare.The phenomenon has been reported from the UK, Canada, northern US states and New Zealand, according to Nasa.Why is it called Steve?The phenomenon has been photographed for decades but only got the name Steve in 2016, following a US citizen science project funded by Nasa and the National Science Foundation.Steve is an acronym for 'Strong Thermal Emission Velocity Enhancement'.Steve is not classified as an aurora but is often associated with its better known cousin, the aurora borealis - or Northern Lights.

While Steve is only spotted in the presence of an aurora, it is not a normal aurora as scientists suggests it comprises of a fast-moving stream of extremely hot particles called a subauroral ion drift.What causes Steve?New research on the phenomenon suggests that the picket-fence aspect of Steve is caused by a similar mechanism as the process that results in an aurora.

Steve's streaks occur when charged particles are heated up high in the atmosphere, further south than typical auroras.

"This occurs outside the auroral zone, so it's indeed unique," Bea Gallardo-Lacourt, a space physicist at the University of Calgary in Alberta, Canada, and co-author of the new research, said in a statement released by the American Geophysical Union, which published the new research.A 2018 study showed that Steve's glow does not result from charged particles falling into the atmosphere, like aurorae.

The authors also pointed out that Steve can show up at the same time as an aurora does, which makes it even harder to figure out which is which.(With inputs from agencies)