On the sixth day of their mission, the Artemis II crew made history. Reaching a maximum distance of 406,771 kilometers (252,756 miles) from Earth at 7:02 P.M. EDT on April 6, they set a spaceflight record, traveling farther from our planet than anyone has gone before. Surprisingly, however, this wasn’t when the crew was farthest from any other human—because at the time some of those other humans weren’t on Earth. The Artemis II crew’s “farthest from humanity” milestone actually occurred about 40 minutes earlier, according to a physicist’s new calculations.

On the day of Artemis II’s lunar flyby, this dispersal of humanity was top of mind for astronauts, scientists and everyday observers alike. The mission’s four astronauts—Reid Wiseman, Victor Glover, Christina Koch and Jeremy Hansen—awoke to a prerecorded message from the late astronaut Jim Lovell, commander of NASA’s Apollo 13 lunar mission, which set the previous record for the farthest-traveled humans in 1970. Lovell wished the Artemis II crew good luck and reminded them “to enjoy the view.” Back on Earth later that day, millions of people enjoyed the view, too, as they watched a livestream of the Orion capsule hurtling toward its fateful flyby. But none of them saw the “farthest distance” record being broken in real time because it occurred while the spacecraft was behind the moon and beyond reach of radio communications.

“Artemis II demonstrated extraordinary skill, courage, and dedication as the crew pushed Orion, SLS (Space Launch System), and human exploration farther than ever before,” said NASA administrator Jared Isaacman in a statement after the record-breaking crew returned to Earth on April 10.

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For astrophysicist Jonathan McDowell, however, the new record posed a minor mystery: Which people, exactly, were the Artemis II astronauts farthest from?

“It was an immediate question in my mind,” McDowell says. “These people are the furthest from the rest of humanity that anyone’s ever been..., but humanity isn’t all in the same place.”

McDowell decided to answer this question himself. Using publicly available data about the location of the Orion capsule, named Integrity, McDowell started his quest by simply figuring out the spacecraft’s antipode—the point on Earth that, from the crew’s perspective, would be opposite and farthest away from them as they reached their maximum distance. He found that it was a remote stretch of the Atlantic Ocean—near 27 degrees north latitude, 68 degrees west longitude—so perhaps some unknowing sailor or fisher set the terrestrial side of Artemis II’s “farthest from humanity” record. But then McDowell realized the answer to who was truly the most remote from that far-flung crew wouldn’t be found on Earth’s surface at all.

While the Artemis II astronauts were making history, 10 other people were in space. Seven crew members were on the International Space Station (ISS), and three were on China’s Tiangong space station. Both space stations were far from the antipode when Integrity reached its maximum distance—but because they were orbiting Earth so quickly, they had come close to that point not long before.

With this knowledge in hand, McDowell began the conversions required to compare the positions of the three spacecraft. Different spacecraft use different clocks and timescales because of the slight relativity-related differences in the way time passes in different parts of space. He took these differing timescales—as well as the tiny precessional changes that shift Earth’s orbit in space—into account in a series of calculations. Then it came down to geometry.

“It’s a really easy calculation once you know where two objects are in space,” McDowell says. “I just had to look at the geometry very carefully to convince myself.”

Running code to calculate the moment-to-moment distances of both space stations with respect to Integrity as the moon mission hit its maximum separation from Earth, McDowell determined that China’s Tiangong space station was slightly farther away from the Artemis II astronauts than the ISS—with the distances being 419,643 and 419,581 kilometers, respectively. At the time and now, the three-person crew of China’s station has consisted of astronauts Zhang Lu, Wu Fei and Zhang Hongzhang, who launched on October 31, 2025, as part of the Shenzhou 21 mission.

Between the ISS and Tiangong crews, it’s not clear which individual astronauts were at the farthest ends of their respective space stations at the critical record-setting moment. With more crewed deep-space exploration on the horizon, however, McDowell suspects the record won’t last long.

“I think what was interesting about this is: it raises the idea of a time when we’re not so much asking, ‘How far are people from Earth?’ but ‘How far are people apart?” McDowell says. “Humanity is going to be scattered around in a way that isn’t so centered on Earth anymore.”