This Scorching Exoplanet Experiences A Steady Pelting Of Iron Rain!


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An artist's illustration of the WASP-76b exoplanet's nightside, which faces away from its sun (Credit: M. Kornmesser/ ESO/CC-By-SA-4.0)

The search for an Earth-like planet that can support life has led to the discovery of many strange worlds, including one with two suns, a lava land, and a shimmering "sapphire" planet. However, none are as extreme or as bizarre as WASP-76b, which boasts 4,352-degree Fahrenheit (2,400-degree Celsius) temperatures, wind gusts of over 10,000 mph, and a steady pelting of iron rain!

"It's a kind of world we can't imagine easily because we don't have anything like that in our solar system," said Christophe Lovis, an exoplanet researcher at the University of Geneva in Switzerland and co-author of the study, published in the journal Nature on March 11, 2020.

Located 640 light-years away from Earth in the constellation Pisces, WASP-76b belongs to a category of giant planets called "ultra-hot Jupiters." The largely gaseous exoplanet's orbit around its sun takes less than two Earth days to complete — a journey so quick that it is tidally locked to its star. This means that only one of the exoplanet's sides gets exposed to its sun, while the other remains in perpetual darkness.​ This is similar to the moon's orbit around Earth, which is why we never see our satellite's "dark side."

The tidal lock causes the temperature between the exoplanet's two sections to vary widely, with the "dayside" creeping past 4,350 degrees F (2,400 degrees C), and the perpetually dark "nightside" hovering closer to 2,732 degrees F (1,500 degrees C). The blistering dayside heat causes the iron molecules present on the planet to vaporize, while the strong winds — the result of the disparity in temperature — transports the metallic gas to the "cooler" nightside. There, it condenses and falls as iron rain.

The rain could consist of compounds such as iron sulfide or iron hydride. But, "Given the conditions, the most likely [scenario] is that iron condenses into liquid droplets of pure iron," says study leader and University of Geneva professor David Ehrenreich. The researcher believes the iron eventually makes its way back to the dayside via atmospheric circulation, perpetuating the cycle.

An artist's illustration of the pelting iron rain on exoplanet WASP-76b (Credit: Frederik Peeters/ ESO/ CC-BY-SA/4.0)

Though scientists have known about WASP-76b and its extreme temperature variations since 2013, the unusual precipitation was only recently uncovered by the University of Geneva team using the European Southern Observatory's Very Large Telescope in Chile, South America. The scientists think the new information about the unusual exoplanet may help researchers finesse and test climate and global circulation models, and lead to a better understanding of exoplanetary atmospheres in general.

"Exoplanets are a real treasure trove full of surprises," Ehrenreich said. "The more you look, the more you find." The University of Geneva team plans to continue surveying other exoplanet atmospheres to see if WASP-76b is an outlier or a member of a peculiar class of worlds, where iron rain is the norm!


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  • peastburn1234
    peastburn1234Friday, March 26, 2021 at 12:17 pm
    good thing earth dosen't rain iron.
    • frenchie_friend
      frenchie_friendMonday, March 8, 2021 at 1:23 pm
      Wow that is so amazing I would touch it if I could but I would get burnt. :O
      • cream
        creamMonday, March 1, 2021 at 11:50 am
        Its so cool I want to go there! (without getting scorched)
        • maria_goodvibes
          maria_goodvibesSaturday, December 12, 2020 at 9:57 am
          That's so cooled I've never seen that before!
          • cream
            creamMonday, March 1, 2021 at 11:50 am
            I agree!
          • cugigefy-160502067384
            cugigefy-160502067384Tuesday, December 1, 2020 at 6:57 am
            I would like to go there and make iron swords.
            • king1294
              king1294Tuesday, November 17, 2020 at 5:54 am
              soooo cool
              • mrzebragamerony
                mrzebragameronyFriday, October 23, 2020 at 8:24 am
                Oh man that is awsome
                • guhee12
                  guhee12Friday, October 23, 2020 at 7:19 am
                  Yea, awsome!
                  • yoyomaster2000
                    yoyomaster2000Tuesday, October 20, 2020 at 6:26 pm
                    That would probably hurt it might be HOT iron rain
                    • flexy-123456789
                      flexy-123456789Tuesday, October 20, 2020 at 8:13 am
                      wow that was awsome