Distant Exoplanet Boasts Iron Rain

(CN) – Astronomers have discovered an exoplanet planet nearly 390 light-years from Earth that features a most peculiar climate phenomenon: iron rain.

In a study published Wednesday in the journal Nature, an international team of researchers reveal the discovery of an exoplanet, dubbed WASP-76b, with such an exotic and diverse climate that it is capable of producing rainfall made of iron drops. Using new technology developed by researchers at the University of Geneva, Switzerland (UNIGE), researchers examined this planet’s strange climate and explain its metallic condensation.

“Singing in the Iron Rain: An Evening on WASP-76b,” by Geneva cartoonist Frederik Peeters.

Researchers say the unique climate activity of the exoplanet is due to one critical planetary detail: a practically double-sided climate. WASP-76b has one side that is virtually always facing in the direction of its nearest star, leaving half of the planet constantly exposed to the overwhelming heat of its sun. Half of the planet experiences constant day while the other is in perpetual night.

The day-portion of the planet experiences extreme temperatures, soaring above 4,352 degrees Fahrenheit. For comparison, the hottest air temperature ever recorded on Earth was 134 degrees Fahrenheit.

WASP-76b gets so hot the metallic compounds found throughout the planet’s atmosphere are vaporized, including significant amounts of iron. Strong winds then carry the vaporized iron to the night-side of the planet where it cools and condenses into droplets of iron pieces which fall on the planet like rain.

This wonderous climate discovery was made possible through a new instrument developed by researchers at UNIGE known as ESPRESSO – the Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations. Placed at the Very Large Telescope in the European Southern Observatory, this new tool gives researchers an astonishing new window into the climates of planets light-years away.

Study co-author Francesco Pepe, professor at the Department of Astronomy of the Faculty of Science at UNIGE and principal investigator of the ESPRESSO consortium, said the researchers were surprised to see just how well this new instrument works for these kinds of observations.

“We thought very early on that we could use the instrument not only to discover new planets, but also to characterize those that are already known. However, until 2018, we didn’t realize how powerful ESPRESSO really was in this field,” Pepe said with the release of the study.

Much of the surprise over the power of ESPRESSO stems from the fact that it was not originally built for this purpose. The new instrument was built to help track down other planets that resembled Earth, particularly those that orbit stars similar to our sun. Scientists discovered after a while, however, that the instrument could be used for much more than that, and that it was uniquely capable at examining far away climates.

David Ehrenreich, first author of the study and a professor in the Department of Astronomy in the Faculty of Science at the University of Geneva, hopes that the technology gives scientists an new tool with which to locate and monitor peculiar climate activity like what has been seen on WASP-76b.

“Thanks to this technology, we now have a completely new way of tracing the climate of the most extreme exoplanets,” Ehrenreich said with the release of the study.

Equipped with this versatile and powerful instrument, scientists are optimistic that continued breakthroughs like this will be made even more possible going forward and that there is no telling what other cosmic climate phenomena await future discovery.

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