So Metal: This Exoplanet Rains Droplets of Molten Iron

Jennifer Leman
Photo credit: ESO

From Popular Mechanics

  • Astronomers have discovered an exoplanet with an atmosphere that rains droplets of molten iron.
  • The tidally locked WASP-76b circles a star in the Pisces constellation, 640 light-years from Earth.
  • Researchers believe temperature differences between the day and night side of the tidally locked planet are responsible.

Meet WASP-76b, the most hardcore exoplanet in the solar system.

The hot gas giant circles a star roughly 640 light-years away in the Pisces constellation. It's also tidally locked with its star, meaning only one side of the planet faces its star. The day and night sides of the planet are vastly different.

"Observations show that iron vapour is abundant in the atmosphere of the hot day side of WASP-76b," said astrophysicist María Rosa Zapatero Osorio, of the Centre for Astrobiology in Madrid, in a press release. The day side is constantly bombarded by radiation and can see temperature spikes of over 4,000 degrees Fahrenheit—hot enough to split open molecules and vaporize metals like iron.

The night side, by comparison, is much cooler, with temperatures around 2,700 degrees Fahrenheit. As atmospheric winds carry the vaporized iron over to the night side, they begin to condense and fall to the surface as rain.

Iron rain. Rain made of IRON. That's so metal.

To make the discovery, Zapatero Osorio and her colleagues used the ESPRESSO instrument (yes, really), part of the European Southern Observatory's Very Large Telescope array. They published their findings March 9 in Nature.

Astrophysicists observed the strongest iron signatures found in the planet's atmosphere during the evening, along the day and night side barrier, which suggests each side has its own unique chemistry.

You Might Also Like