ILLUMINATING THE NIGHT: THE ENIGMATIC JOURNEY TO DISCOVER STEVE AND ITS MYSTERIOUS TWIN

It’s a saga from space, a story of science and discovery: STEVE came into the picture in 2016 as a purple-and-green haze that didn’t quite seem part of the aurora. Now, it seems there’s also a shadowy side to STEVE – and it’s moving in the opposite direction.

DISCOVER STEVE: A PHENOMENON UNLIKE ANY OTHER

It was nicknamed STEVE, an acronym for Strong Thermal Emission Velocity Enhancement, a reference to STEVE the porcupine from the kid’s movie Over the Hedge. Its discovery by citizen scientists identified something different from the usual sights of auroral light. STEVE’s purple streaks cut across the sky, unlike the shapes of typical aurora. The colour of the light was different, too: STEVE is short-lived, unlike the bright tones usually created by the solar wind streaming along Earth’s magnetic field lines to react with atmospheric atoms and molecules.

THE QUEST TO DISCOVER MORE: UNCOVERING STEVE'S TWIN

That quest to better understand STEVE sent investigators into archives: there, they found images of an eastern-moving twin (found in the Norwegian Arctic). This finding is exciting, not only because of the unique story it adds to the sprite AD saga, but also because such a large feature presents unique opportunities for exploring what processes create these beautiful displays.

A COMMUNITY EFFORT TO DISCOVER: CITIZEN SCIENTISTS AT THE FOREFRONT

Citizen scientists like Gabriel Arne Hofstra have added to the story by hunting down STEVE’s twin, which he spotted in an image taken in December 2021. The story has been a testament to the power of public curiosity conserved in collaboration with scientists, whose work has extended human knowledge beyond our planet, into the deep frontier of space.

DISCOVERING THE MECHANISMS BEHIND STEVE AND ITS TWIN

Unlike auroras, which are driven by the solar wind streaming into the Earth’s atmosphere and colliding with gas molecules, STEVE and its sibling are running along a stream of highway made up of extremely hot gas – a phenomenon called sub-auroral ion drift, as it flows along distinct magnetic field lines below the auroral oval. These antics allow the STEVE lookalike to appear at more southerly latitudes than one would expect a full-blown aurora to occur, entertaining a whole other audience.

THE PATH OF DISCOVERY: METHODS AND TOOLS

STEVE’s twin was detected in a careful reanalysis of archival images and with data from the European Space Agency’s Swarm satellites. No single satellite measurement captured the twin as it streaked across the sky, but the combination of tools and methods allowed scientists to trace the ion flow within the purple ribbon.

THE ENDLESS QUEST TO DISCOVER: WHAT LIES BEYOND

With discoveries such as STEVE and its enigmatic twin, the night sky has just become a bit bigger, and the intangible sources of sky-phenomena are ever more intricate and intriguing. In time, STEVE and other green flashes will be solved, whose answers will undoubtedly spark yet more questions. But, thanks to science and the public, the night sky – and mysteries that reside within it – will continue to become slightly more transparent.

THE ROLE OF DISCOVER IN UNVEILING THE UNIVERSE

STEVE and its cousin story is about the role of discovery in a quest to understand the Universe, in a quest without end. Sometimes, working together, we can expand that horizon into a whole new landscape. Discovery – in astronomy and in more mundane matters that touch our everyday lives – is all about innovation. It asserts, again and again, that there’s more to explore, and more ways of making exploration happen.

Next time you find yourself gazing at the stars in a dark sky, remember that each flaring cluster, each rogue streak of light, and each ethereal hue tells a story. Finding our way to interpret what’s real and what’s fake in STEVE and its virga counterpart is but a glimpse of future explorations surveying our celestial firmament. What we discovered will serve as another small spark in what promises to be a mighty inferno of discovery.

Let us remain true to the spirit of discovery, whose observing telescope allows us to see phenomena where there was none before, and to continue to explore the tapestry of the Universe left for us to unveil. Scientists and citizen observers alike continue to show us that there is no limit to the rewards of exploration.