What time is it on the Moon? Satellite navigation systems for lunar settlements will require some local atomic clocks. Hear about it on urban legends and stranger truths. The coming decade will see a resurgence in lunar exploration that includes dozens of missions and plans to establish permanent bases on the moon. The endeavors pose a lot of challenges. Among them is a subtle but fundamental question that scientists worldwide are working to answer. And that is, what time is it on the moon?