This exoplanet is 390 light years away towards the constellation Pisces.

It has days when its surface temperatures exceed 2,400 Celsius, sufficiently hot to evaporate metals.

Its nights have strong winds that cool down the iron vapor so that it condenses into drops of iron.

With ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations), chemical variations between day and night on the planet are identified.

The trace of iron vapor just at the division between the daytime and the night-time sector of the planet is detected. It is the first time that chemical variations have been detected in a giant ultra-hot planet. 

According to a researcher, this iron vapor at dawn is not seen. The only explanation possible for this phenomenon is that it rains iron on the dark side of this exoplanet with extreme conditions.

The observations show a huge quantity of iron in the daytime atmosphere of the giant planet WASP-76b. A part of this iron is transported to the dark side of the planet due to its rotation and the atmospheric winds. There in the cooler environment of the dark side of the planet, the iron condenses and precipitates.

Just like the Moon around the Earth, this planet always keeps the same face towards its star as it rotates around it, which causes this extreme difference in temperature between day and night on the planet.

WASP-76b receives thousands of times more radiation from its central star than arrives at the Earth from the Sun. Its daytime face is so hot that the molecules split into atoms, and metals such as iron evaporate into the atmosphere. The difference of more than a thousand degrees between night and day produces strong winds that take the iron vapor into the coolest part of the exoplanet.

If an exoplanet is studied during its transit across the disc of its star, the part of its atmosphere through which the light from the star passes can be studied.