What Is STEVE, the Mysterious Ribbon of Light in the Night Sky?

STEVE is a glowing ribbon of superheated plasma that stretches across the night sky for up to 600 miles, produced by a fast-moving river of hot ions flowing through the upper atmosphere — and it is entirely distinct from the northern lights.

What Does STEVE Stand For?

The name STEVE stands for Strong Thermal Emission Velocity Enhancement — but the acronym came after the nickname. Aurora-chasing enthusiasts in Alberta, Canada spotted the strange mauve-and-white ribbon and named it “Steve” as a lighthearted placeholder, borrowing from the animated film Over the Hedge, where characters name an unknown thing simply to feel better about it. Researchers later reverse-engineered the acronym to fit. The name stuck. The science followed.

How Is STEVE Different From the Aurora Borealis?

This is the key distinction. The northern lights — aurora borealis — are produced when energetic charged particles from the Sun rain down along Earth’s magnetic field lines and collide with atmospheric gases. STEVE operates through a completely different mechanism. ESA’s Swarm satellites flew directly through STEVE and detected a narrow channel of superheated ions moving westward at nearly four miles per second (roughly 13,000 mph). These ions are not raining downward — they are racing laterally through the subauroral zone of the upper atmosphere, at altitudes between 65 and 90 miles above Earth’s surface.

Scientists formally confirmed in a 2018 paper published in Science Advances that STEVE is a new and separate category of optical atmospheric phenomenon. Its glow comes not from particle precipitation, but from the intense friction and heat generated by that plasma river tearing through the surrounding gas.

How Hot Is STEVE?

The plasma inside STEVE reaches temperatures of approximately 5,400°F (3,000°C) — hotter than the surface of some red dwarf stars. This extraordinary thermal energy is what produces its distinctive narrow ribbon appearance: mauve or purple at the core, sometimes flanked by a “picket fence” of green-and-white vertical streaks caused by related particle activity at the edges.

Where and When Can You See STEVE?

Unlike the northern lights, which require high-latitude locations such as Norway, Iceland, or northern Canada, STEVE has been observed at surprisingly low latitudes. Sightings have been confirmed over the United Kingdom, the northern United States, and even New Zealand — well outside the typical auroral zone. It tends to appear during periods of moderate to strong geomagnetic activity and can remain visible for up to a full hour, far longer than many auroral displays.

Hidden in Plain Sight for Centuries

Perhaps the most striking aspect of STEVE is that it has almost certainly appeared in skies throughout recorded human history. Because it resembles — but predates confusion with — the aurora borealis, observers likely filed it away as an unusual aurora and moved on. No scientific framework existed to flag it as something separate. It was citizen scientists armed with modern cameras and online communities who finally accumulated enough sightings to demand an explanation. Without that grassroots documentation effort, STEVE might have remained unnamed and unstudied for decades more.

What Does STEVE Tell Us About Earth’s Magnetic Field?

STEVE’s existence reveals that Earth’s magnetosphere has more complexity and more dynamic behaviour than previously understood. The plasma flow that generates STEVE is linked to subauroral ion drifts (SAIDs) — fast-moving channels of plasma that form when energy from solar storms is redistributed through the magnetosphere unevenly. STEVE is, in effect, a visible signature of those energy flows — a glowing seam where the system is working hardest. Studying it gives scientists a new window into space weather and the ways our planet’s magnetic shield responds to pressure from the Sun.