A spacecraft successfully landed on a comet for the first time in human history, as people around the world watched a mission control room in Darmstadt, Germany, await confirmation that Rosetta's Philae lander touched down on its icy surface.
European Space Agency, which oversaw Rosetta's decade-long mission to study comets, confirmed the landing on the comet, better known as 67P/Churyumov-Gerasimenk in space parlance.
Scientists at mission control celebrated the touchdown like a touchdown.
Even William Shatner was impressed.
Though, arguably, no one was more excited than this guy.
His camera-directed first-pump quickly became an Internet meme.
One Twitter user celebrated the comet landing using Lego bricks.
Others pointed out Philae's resemblance to another high-flying spacecraft.
Dr. Matt Taylor, one of the mission's lead scientists, threatened to steal the spotlight as BBC viewers took notice of a shirt emblazoned with scantily clad women ...
... and a leg tattoo that depicted Philae landing on the comet.
As the world (and Twitter) waited, many shared these simple, explanatory diagrams of what was going on.