For the first time, potential signs of the rainbow-like ‘glory effect’ have been detected on a planet outside our Solar System. Glory are colourful concentric rings of light that occur only under peculiar conditions.
Data from ESA’s sensitive Characterising ExOplanet Satellite, Cheops, along with several other ESA and NASA missions, suggest this delicate phenomenon is beaming straight at Earth from the hellish atmosphere of ultra-hot gas giant WASP-76b, 637 light-years away.
Seen often on Earth, the effect has only been found once on another planet, Venus. If confirmed, this first extrasolar glory will reveal more about the nature of this puzzling exoplanet, with exciting lessons for how to better understand strange, distant worlds.
Data from Cheops and its friends suggest that between the unbearable heat and light of exoplanet WASP-76b’s sunlit face, and the endless night of its dark side, may be the first extrasolar ‘glory’. The effect, similar to a rainbow, occurs when light is reflected off clouds made up of a perfectly uniform but so far unknown substance.
“There’s a reason no glory has been seen before outside our Solar System – it requires very peculiar conditions,” explains Olivier Demangeon, astronomer at the Instituto de Astrofísica e Ciências do Espaço (Institute of Astrophysics and Space Sciences) in Portugal and lead author of the study.
“First, you need atmospheric particles that are close-to-perfectly spherical, completely uniform and stable enough to be observed over a long time. The planet’s nearby star needs to shine directly at it, with the observer – here Cheops – at just the right orientation.”
If confirmed, this first exoplanetary glory would provide a beautiful tool to understand more about the planet and star that formed it.
“What’s important to keep in mind is the incredible scale of what we’re witnessing,” explains Matthew Standing, an ESA Research Fellow studying exoplanets.
“WASP-76b is several hundred light-years away – an intensely hot gas giant planet where it likely rains molten iron. Despite the chaos, it looks like we’ve detected the potential signs of a glory. It’s an incredibly faint signal.”
This result demonstrates the power of ESA’s Cheops mission to detect subtle, never-seen-before phenomena on faraway worlds.
WASP-76b is an ultra-hot Jupiter-like planet. While it is 10% less massive than our striped cousin, it is almost double its size. Tightly orbiting its host star twelve times closer than scorched Mercury orbits our Sun, the exo
