In the past two decades, telescopic and remote sensing observations have found craters near the poles of the Moon and Mercury harbor ice deposits inside permanently shadowed regions. On Mercury, evidence gathered by the Arecibo radio telescope and the MErcury Surface, Space ENvironment Geochemistry and Ranging spacecraft (MESSENGER) have determined the ice deposits are pure and at least a few meters thick. In contrast, parallel observations conducted on the Moon found little evidence for similarly thick ice deposits. This difference came across as surprising since the surface conditions on the two planetary bodies are relatively similar. A new study led by UCLA planetary scientists Lior Rubanenko, Jaahnavee Venkatraman (BS Statistics ’18), and David Paige suggests the Moon and Mercury may not be so different after all. The researchers found small craters near the north pole of Mercury and the south pole of the Moon are shallower relative to craters in lower latitudes, and concluded this shallowing is due to the accumulation of thick ice deposits on their floors. If confirmed, this new discovery may not only solve the question of the apparent difference between the poles of Mercury and the Moon, but may also help sustain a future long-term mission on the moon.