NASA's Cassini spacecraft captured a photo of a methane rainstorm concentrated near the equator of Saturn's largest moon, Titan. The picture was taken on October 18, 2010. More info at Space.
When photos showed a large patch near the equator of Titan mysteriously darken and then grow lighter within a couple of weeks, scientists knew something big was happening on Saturn's largest moon. But what they found was something they didn't expect: a methane rainstorm in a region of Titan thought to be covered by vast, arid dunes.
While the large moon is known to have methane lakes at its north and south poles, scientists thought Titan's equatorial region was mostly dry, but the likely cause of the darkness was determined to be an outburst of clouds and methane rain — which suggests Titan's equator has a rainy season.