Precipitation is much more widespread throughout that solar system than commonly assumed. Obviously it rains water on Earth. But it snows carbon dioxide on Mars, rains methane on Titan, sulfuric acid on Venus, and could potentially rain diamonds on Neptune. The type of material falling out of the sky is almost as varied as the planets themselves. New research from a team led by Kaitlyn Loftus at Harvard found a similarity for all of the liquid materials that constitute rain throughout the solar system – all of the drops, no matter the material, are roughly the same size.