Tranquility and Serenity

Saturday 25th July 2026

Those calm dark patches are the Seas of Tranquility and Serenity, or Mare Tranquillitatis and Mare Serenitatis in Latin. They're not actually seas at all. They're ancient lava flows that filled up massive impact basins on the Moon, which is why they look so smooth and dark against the bright, crater-covered highlands surrounding them. You can even spot them with the naked eye.

Here's the bit that gives me chills: back on 20 July 1969, the Apollo 11 lunar module Eagle touched down right in the Sea of Tranquility, on the lower right side of this view. That's where humans first set foot on another world, right there in that calm, dark patch of ancient lava.