Astronaut Chris Hadfield's Story and David Bowie Fame

Astronaut Chris Hadfield performed aboard the International Space Station a revised version of David Bowie's song Space Oddity, May 12, 2013. Chris Hadfield/CSA NASA, via EPA

"You can't make out borders from up here."

Chris Hadfield beamed live into a studio somewhere in Canada, Earth rotating outside his window and a guitar floating near his lap, and began to sing. From the bowels of the International Space Station, which he had commanded since December, the Canadian astronaut joined the Barenaked Ladies and a children's choir for what should have been a fiercely nationalistic moment: "the first space-to-earth musical collaboration," to be aired across the country on the Canadian Broadcasting Corp.

But the 53-year-old Hadfield infused his song with the same spirit of globalism that he has been preaching—if subtly—over his five months in space. Beneath the tweets and YouTube videos that have made him an Internet sensation (he has more than 900,000 Twitter followers) lies a message of unity in a divided world—a perspective, perhaps, that only comes 230 miles above Earth's surface.

"Syria—deceptively calm and beautiful," he wrote in a tweet on January 2, 2013, attaching a photo of the country's shoreline. "Peaceful from such a distance."

"The world just unrolls itself for you, and you see it ... as one place," he explained in a later video.

While his most popular posts make the mundane magical—did you know it's impossible to cry in space? (2 million views); you can't wring out a cloth, either (7 million views); watch these mixed nuts float around! (5 million views)—Hadfield brought both physics down to earth (as it were) and viewers from around the world together to admire the shared marvels of our universe.

On Sunday he handed over his command to Russian Pavel Vinogradov and on Monday returned to Earth alongside Roman Romanenko, also Russian, and American Tom Marshburn, finding time in between to post his own music-video cover of David Bowie's "Space Oddity."

Next up? He changed his listed location on Twitter—from "Orbiting Earth on ISS" to "In a field in Kazakhstan" upon landing—and will continue to spread his message on Earth.

"This is a spaceship," he said while aboard the ISS, "but so is the world."