Lou Momège // Photo credits: European Space Agency (ESA) 5:16 p.m., April 5, 2024

According to observations from the European Cheops telescope, there is an immense circular rainbow on the exoplanet WASP-76b, which is located 637 light years from our Earth. This was announced by the European Space Agency in a press release published this Friday, April 5.

For the first time, scientists have observed potential signs of a rainbow outside our solar system, according to a press release from the European Space Agency, published this Friday. This optical phenomenon is similar to a glory, that is to say concentric circles of colors, formed by light, which only takes shape under very specific conditions. 

A phenomenon of glory observed

Common on Earth, when light is filtered by water droplets, this rainbow phenomenon has only been seen on one other planet: Venus. If the glory phenomenon is indeed confirmed on WASP-76b, this could allow us to better understand this exoplanet and learn more about the environments that are still foreign to us in space. 

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Since the discovery of WASP-76b in 2013, 637 light years from planet Earth, the exoplanet has been the subject of the greatest attention from European astronomers. Data collected by the European space telescope Cheops suggests that a glory outside the solar system exists, thanks to a source of light and intense heat on one of the faces of the exoplanet WASP-76b, but also its submerged part constantly in the dark. 

Have astronomers detected the first ever extrasolar 'glory'?



Potential signs of the rainbow-like 'glory effect' have been detected on a hellish planet outside our Solar System.



The team used data from @ESA_CHEOPS & other missions https://t.co/hSQ8XKoEeWpic.twitter.com/wXXQRcUrJN

— ESA Science (@esascience) April 5, 2024

The effect produced, similar to that of a rainbow, is due to the restoration of light in kinds of clouds, the material of which remains unknown for the moment. This discovery therefore does not allow us to affirm that there is water on WASP-76b. Confirmation of a glory effect would, however, make it possible to ensure the presence of a cloud, formed of "perfectly spherical droplets, existing for at least three years, or which are constantly renewed", according to the European Space Agency. 

An unlivable planet

Despite the presence of a semblance of a rainbow on WASP-76b, the exoplanet is far from idyllic and adapted to human needs. Its temperature reaches around 2,400 degrees Celsius. One of its faces is in fact constantly directed towards the Sun, while the other, colder, is always plunged into darkness. All the elements that form rocks on our planet therefore melt on the hot side, and end up condensing while cooling on the other, colder side. This phenomenon helps form clouds, which rain molten iron.

The presence of a rainbow in the form of glory could therefore mean that the atmosphere is very stable on the exoplanet, and that the rains of molten iron are almost constant. A world that looks like hell, according to the European Space Agency.