WASP-76 b: The Exoplanet That Rains Molten Iron

Among the planets in the universe which have crazy weather conditions, is the newly discovered WASP-76 b, which has been dubbed the “ultra hot Jupiter”. 

WASP-76 b is incredibly hot, so hot in fact, that it actually rains molten iron from the sky. 

The exoplanet is situated in the Pisces constellation, around 640 light-years away from Earth, and is as large as Jupiter, but nearly twice the width. 

WASP-76 b is in close orbit with its primary star WASP-76, and completes a full orbit in a rapid 1.8 Earth days, an incredibly short amount of time given the time it takes our closest planets to orbit the Sun. Mercury is the closest planet to the Sun, and it takes 88 Earth days for Mercury to complete a full orbit. 

Only one side of WASP-76 b is ever facing WASP-76, which means the exoplanet is “tidally locked”. The planet also experiences incredibly volatile temperatures, at around 2,400 degrees Celsius, high enough to completely vaporize metals. The side which is always facing away from its host star, is referred to as the “nightside”, and records temperatures of around 1,500 degrees Celsius.

David Ehrenreich, who is an associate professor of astronomy at the University of Geneva in Switzerland said: “These are likely the most extreme climates we could ever find on a planet.”

The Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) was used in studying the exoplanet, when researchers witnessed a considerable amount of iron vapor situated near the “evening” border. This is the border which separates the dayside from the nightside. Researchers concluded that there were no signs of iron located at the “morning” border, which can be found on the opposite side of the exoplanet.

They concluded that WASP-76 b rains molten iron. 

Ehrenreich claimed: “Something must be happening on the nightside that makes iron disappear,”. He also went on to say: “One could say that this planet gets rainy in the evening – except it rains iron,”. 

Weather conditions are indeed extreme on WASP-76 b, even seeing winds reach speeds of around 11,000mph. These strong winds are probably the reason for the molten iron being carried from the dayside to the nightside of the planet, where it condenses into clouds full of iron droplets and begins raining iron.

Exoplanets continue to surprise scientists, with WASP-76 b one of the latest to add to the list.