Ferrous droplets fall
on the nightside of poor locked
WASP. A fishy place.
In the constellation Pisces, 640 light years away from Earth, there is a planet that orbits so closely to its star that it rains iron.
A team of around 100 researchers (Ehrenreich et al, 2020) used the European Southern Observatory’s Very Large Telescope in Chile to observe the vast exoplanet WASP-76b and found that temperatures reach above 2400 degrees Celsius, hot enough for iron to vaporise.
WASP-76b is tidally locked, meaning that its spin and rotation around its star coincide, with one side of the planet always in darkness and one side always facing the star – in the same way that our moon always presents the same side to the Earth. Strong winds are created as a result of a temperature difference of around 900 degrees Celsius between the sun-facing dayside and the perpetually dark nightside. Iron is vapourised on the dayside and these winds carry the iron vapour to the cooler side of the planet where it condenses and rains down.
A note about “A fishy place” – this is a reference to WASP-76b’s location in the constellation of Pisces, which in astrology is the sign of the fish.
Original research: https://doi.org/10.1038/s41586-020-2107-1