In all our searching of the universe, we’ve never seen another moon like ours. It's big, it's weird, and it has played a huge role in shaping our planet. But how did we get it? Every possible story points to cataclysm.This episode originally ran on June 15, 2022. It is part of our Lost Worlds series exploring scientific mysteries buried in the deep past.For more, go to http://vox.com/unexplainableIt’s a great place to view show transcripts and read more about the topics on our show.Also, email us! unexplainable@vox.comWe read every email.Support Unexplainable by making a financial contribution to Vox! bit.ly/givepodcastsLearn more about your ad choices. Visit podcastchoices.com/adchoices