Scientists discover for the first time the “glory effect” on a planet outside our solar system

(CNN) — A group of astronomers have discovered for the first time what they believe is a rainbow-like phenomenon on a planet outside our solar system, and it could reveal new insights into distant worlds.

Observations by the European Space Agency's Cheops Space Telescope, or exoplanet satellite, revealed a “glory impact” on WASP-76b, an extremely hot exoplanet located 637 light-years from Earth.

An artist's illustration shows a concentric, rainbow-like phenomenon called the glory effect detected in the atmosphere of exoplanet WASP-76b. Which

Glory, often seen on Earth, consists of colorful, concentric rings of light, and occurs when light reflects off clouds made of uniform material.

Beyond Earth, the Glory Impact had only been seen on Venus until Khufu and other missions picked up an incredibly weak signal indicating it was occurring in the atmosphere of the superheated exoplanet WASP-76b. Based on the signal detected by Khufu, astronomers believe that the atmospheric phenomenon occurs directly in front of the Earth.

The researchers published details of the observation on April 5 in the journal Astronomy and astrophysics.

“There's a reason the glory has never been seen outside our solar system: it requires very strange conditions,” the study's lead author, Olivier Demanjon, an astronomer at the Portuguese Institute of Astrophysics and Space Sciences, said in a statement. “First, we need atmospheric particles that are almost perfectly spherical, perfectly uniform, and stable enough to observe for a long time. A star close to the planet needs to be shining directly on it, with the observer (in this case Khufu) facing in the right direction.”

A wild and burning planet

WASP-76b has aroused the interest of astronomers since its discovery in 2013.

The exoplanet orbits close to its host star, and the intense heat and radiation from this Sun-like star (more than 4,000 times the amount of radiation Earth receives from our Sun) caused WASP-76b to swell, making it nearly double the size of Jupiter, the largest planet in our system. .

A simulated view shows glory as it might appear on Venus (left) and Earth. C.Wilson/B. Lavender/ESA

The planet is in synchronous rotation with its star, meaning that one side, known as the day side, always faces the star, while the other side of the planet is always at night.

The dayside of WASP-76B reaches scorching temperatures of 4,352°F (2,400°C). The elements that make up rocks on Earth melt and evaporate on the dayside before condensing and forming clouds that release rains of molten iron on the nightside.

Astronomers decided to devote a large number of observatories, including Cheops, the Hubble Space Telescope, the now-retired Spitzer Space Telescope, and NASA's planet-hunting TESS mission, to study what appears to be a light imbalance that occurred while WASP-76b was orbiting. . In front of its host star.

Data combined from Cheops and TESS, or the Transiting Exoplanet Survey Satellite, indicated that this anomaly might be due to something interesting happening in the atmosphere above the day.

Khufu captured data from WASP-76b as the planet passed in front of its star, and made 23 observations over three years.

When astronomers looked at the data, they noticed an unusual increase in light coming from the planet's eastern “terminator,” or the boundary light between the day and night sides. Meanwhile, the western terminator emits less light.

“This is the first time such a sharp change in the brightness of an exoplanet, or its phase curve, has been detected,” Demangione said. “This discovery leads us to the hypothesis that this unexpected glow could be caused by a strong, localized, anisotropic (direction-dependent) reflection: the glory effect.”

Demangione said he was happy to participate in the first discovery of this type of light from an exoplanet.

“It was a special feeling, a special relief that doesn't happen every day,” he said.

Colorful light on strange worlds

Glory and rainbows are not the same thing. A rainbow is produced when light bends as it passes successively through two media of different densities, such as air to water. When light is bent, it splits into different colors, creating a rainbow.

But the glory effect arises when light moves through a narrow aperture and bends, creating patterned rings of color.

If astronomers are indeed seeing a glory effect on WASP-76b, it means the planet has persistent clouds made of perfectly spherical blobs, or clouds that are constantly renewing. In either case, the presence of such clouds indicates that the temperature of the planet's atmosphere is stable.

The exact nature of what is in WASP-76b's clouds remains a mystery, but it could be iron, as the element has previously been discovered in the planet's clouds.

An artist's illustration shows a night view of the exoplanet WASP-76b, with iron falling from the sky. M. Kornmesser/ESO

“It is important to note the staggering scale of what we are witnessing,” Matthew Standing, a researcher at the European Space Agency who studies exoplanets, said in a statement. Permanent did not participate in the study.

“WASP-76b is several hundred light-years away: an extremely hot gas giant planet is likely showering molten iron,” Standing said. “Despite the chaos, (researchers) seem to have detected possible signs of glory. “It's an incredibly weak signal.”

If astronomers can observe the faint signal of a phenomenon like a glory hundreds of light-years away, it will also be possible in the future to detect the presence of sunlight reflected from extraterrestrial bodies of water, according to the researchers.

“More evidence is needed to definitively say that this interesting ‘extra light’ is a rare glory,” Teresa Loftinger, project scientist for ESA’s Ariel mission, said in a statement. She did not participate in the study.

Ariel, or the Large Infrared Survey for Remote Sensing of Exoplanetary Atmospheres, is expected to launch in 2029 to study the atmospheres of a wide and diverse range of exoplanets.

Loftinger said he believes the James Webb or Ariel Space Telescope could help test the presence of the Glory Effect in WASP-76b.

“We may find even more spectacular colors shining on other exoplanets,” he said.