Strange light spotted over distant 'hell planet' may be 1st rainbow 'glory' found beyond our solar system

Astronomers think they've detected an extremely rare, luminous phenomenon known as a "glory" in the hellish atmosphere of a distant exoplanet. If the finding is confirmed, it would be the first time one of these rainbow-colored light shows has been spotted outside the solar system.

The exoplanet, WASP-76 b, is located around 637 light-years from Earth. It was first discovered in 2013 by the Wide Angle Search for Planets (WASP) project, which looks for planets as they pass between, or transit, their parent star and Earth.

The exoplanet — which may have cannibalized a smaller, Mercury-size neighbor in the past — is around 90% the mass of Jupiter but about twice as wide. It is unusually close to its home star, orbiting around 20 times closer than Mercury orbits the sun. As a result, it takes WASP-76 b just 1.8 days to complete one trip around its star.

In 2020, researchers discovered that the planet is tidally locked, meaning one side is always facing its home star, just as the moon faces Earth. As a result, the exoplanet's sunlit side is around 4,350 degrees Fahrenheit (2,400 degrees Celsius), while its dark side is slightly cooler. Researchers think that, due to this subtle temperature difference, metals like iron could be vaporized on the light side and then condense into rain on the dark side.

In a new study, published April 5 in the journal Astronomy & Astrophysics, researchers examined new data on WASP-76 b collected by multiple spacecraft, including the European Space Agency's (ESA) Characterising Exoplanet Satellite and NASA's Transiting Exoplanet Survey Satellite. This analysis revealed a "bright spot" of light coming from the exoplanet's eastern limb, along the boundary where the planet's permanent day and night meet.

The researchers think this bright spot could be a "glory." This rare visual phenomenon, when seen on Earth, is normally made up of concentric rainbow rings forming a giant circle.

Related: 10 extreme exoplanets that are out of this world