Rain on Earth is usually made of liquid water, but distant worlds can have completely different forms of precipitation. On Saturn’s moon Titan, methane moves through the atmosphere in a cycle similar to Earth’s water cycle, producing methane clouds, rain, rivers, and lakes. Deep inside Neptune, extreme pressure and temperature may cause carbon-rich material to form diamond crystals that sink downward, creating what scientists often call “diamond rain.” On the ultra-hot exoplanet WASP-76b, iron can become vapor on the scorching dayside and may condense on the cooler side. These strange environments show how dramatically planetary weather can change across the universe.
