On frigid Titan, these rains aren't balmy showers—they're made of liquid methane, a substance found on Earth as the principal ingredient in natural gas.

The finding is just the latest evidence that Titan has a "methane cycle" similar to Earth's water cycle.

Previously scientists had found methane lakes near Titan's poles, and later discoveries of fog over the lakes and lake effect clouds suggested that, as water does on Earth, the lakes' liquid methane may evaporate and enter the atmosphere.

What's more, the appearance of new lakes at the south pole showed that Titan's clouds likely produce cold methane rain over the poles.

But so far the