Presbyterian theology recognizes that taking communion all by yourself is a pretty weird thing to do (lunar or otherwise). So Aldrin and his pastor had worked things out in advance: The lunar landing was on a Sunday, and Aldrin’s home church celebrated their earthling communion service in a way that recognized one of their church members was way off in space, communing along with them.
He also points to this site for more information, including an excerpt that Aldrin wrote about the experience a few decades later:
"I ate the tiny Host and swallowed the wine. I gave thanks for the intelligence and spirit that had brought two young pilots to the Sea of Tranquility. It was interesting for me to think: the very first liquid ever poured on the moon, and the very first food eaten there, were the communion elements."
P.S. Yes, I think my post title is quite clever, thanks.