For one hot, faraway world, the forecast is rain. Iron rain. WASP-76b is so scorching that iron vaporizes in the atmosphere. POOF! 

The mysterious iron-raining mega-planet is 390 light-years away. Astronomers noticed that its clouds are full of metal droplets. They think iron condenses on the cool night side of the planet. That’s where it turns to rain. Scientists watch the planet’s weather patterns. They see it with a new instrument on the European Southern Observatory’s Very Large Telescope in Chile.

It’s “like droplets of metal falling from the sky,” says Christophe Lovis of the University of Geneva, Switzerland. He’s part of the research team doing the study. It will appear in the journal Nature. Imagine melted metal dripping out of a cloudy sky!             

Planet WASP-76b is nearly two times the size of Jupiter. It’s always daytime on the side of the planet that faces its star. The sky stays clear, and you can imagine it’s hot there—4,350 degrees. It is always nighttime on the other side of the planet. There, temps drop down to a mere 2,700 degrees. The sky on the “cool” side stays overcast with iron rain.

Strong wind gusts across WASP-76b. Wind bursts exceed 11,000 mph. They sweep some of the iron vapors from the day side to the night side of the planet. Cooler weather on the night side causes clouds to form. Curiously, iron vapor isn’t around in the morning. That’s probably because it rains on the night side. The iron clouds burst when they become full of iron raindrops. 

Isn’t the climate on WASP-76b crazy? It’s the only faraway world where iron has been spotted dripping from the sky. Is its iron rain a drenching downpour or a light drizzle? So far, scientists can’t tell.  

But one thing’s certain: It’s not raining cats and dogs. Just iron.