A few years before Jim Lovell and Buzz Aldrin would make lunar history—Lovell as one of the first astronauts to orbit the moon in 1968 and Aldrin as the second man to walk on it in 1969—the two Americans sat together inside the Gemini 12 cockpit some 200 miles above Earth.
It was November 1966, and they had docked to the Agena spacecraft, a maneuver Gemini astronauts practiced in preparation for future lunar travels. But in this moment, their attention was focused elsewhere.
Soon, darkness began to spread around them. Aldrin pointed his camera and Lovell aligned the spacecraft as the moon passed in front of the sun. “The eclipse got to us after all,” Lovell said over radio airwaves, when the men realized they would get a chance to see it.
Orbiting just about three miles away from the path of totality’s center, they watched as parts of South America were blanketed in shadow. It was the first total solar eclipse ever witnessed from outer space.
Now, almost 60 years later, astronomers look back on that moment with affection and measured curiosity. Nearly as notable as the eclipse itself, however, were the circumstances that led Aldrin and Lovell to observe it. Their mission was not initially set to overlap with the eclipse, and the two men were not even the original crew for the flight. If not for the deaths of Gemini 9 astronauts Elliot See and Charles Bassett, a delayed launch and a malfunction of the Agena’s thrusters, the pair wouldn’t have been on that spacecraft, at that exact time, for that unprecedented experience.
“It was really just happenstance, honestly, that the path of Gemini 12 passed through that shadow,” Andrew Johnston, the vice president of astronomy and collections at the Adler Planetarium in Chicago, tells Smithsonian magazine. As the last flight of the Gemini program, the mission’s main focus was on testing techniques needed for getting to the moon. The eclipse was just a happy coincidence.
“As with most phenomena in space, timing is everything,” says Jennifer Levasseur, a space history curator at the National Air and Space Museum, to Smithsonian magazine. “Their mission didn’t launch because of the possibility of an eclipse. [Gemini 12] is more known for its other accomplishments.”
As further evidence of their unpreparedness, Aldrin’s camera wasn’t suited to clearly image the sun, hence the star appearing as a “fuzzy blob” in his photograph, Johnston says. None of the images entered the pantheon of iconic space photos, he adds.
“It was more indicative of the kinds of things you can see from space,” he says. “A moment in time during the race to the moon.”
When astronauts witnessed total solar eclipses from space
Since 1966, no space mission has been specifically dedicated to observing a total solar eclipse. But a select few astronauts have been lucky enough to witness eclipses that coincided with other directives.
“Not many people get to see solar eclipses, even on the surface of Earth,” Johnston says. “Which is a shame, because they’re the most beautiful thing you’ll ever see. But seeing them from space is even more unusual.”
Crew members on Apollo 11 and Apollo 15 got rare views of eclipses as they rounded the moon in 1969 and 1971. As the Apollo 11 astronauts circled in lunar orbit right after sunrise, they captured photographs on 70-millimeter film of “the glow of the corona before the rest of the sun itself came up over the edge of the moon,” Johnston says. The moment was the second eclipse from space witnessed by Aldrin. During Apollo 15, the astronauts didn’t manage to take a picture.
Now, astronauts who witness solar eclipses do so from the International Space Station (ISS). But instead of looking at the sun, they look down at the Earth to observe a solar eclipse. “ISS astronauts can see the [moon’s] shadow but not the eclipse itself, because their windows don’t point toward the sun,” says Levasseur. Rather, remotely operated equipment on the station collects data from the eclipse, while astronauts peer at the darkened ground on the planet below.
The first time anyone got this unique view was in 1999, when Russian cosmonauts Viktor Afanasyev and Sergei Avdeyev, as well as French astronaut Jean-Pierre Haigneré, witnessed the 20th century’s final total solar eclipse from the former Russian space station, Mir. On August 11, they saw the moon’s shadow pass over England.
Don Pettit—an American astronaut famous for creating the “Zero-G coffee cup,” the first object invented in space to receive a patent—has witnessed two total solar eclipses from orbit, in 2002 on Expedition 6 and in 2012 on Expedition 31. The crew of Expedition 12 also witnessed a solar eclipse in 2006, above Turkey and the Mediterranean Sea.
“Orbital sunrise and the solar eclipse... could it go any better?” Italian astronaut Samantha Cristoforetti, a flight engineer on Expedition 43, wrote on social media in 2015, when astronauts saw a solar eclipse that passed over parts of Europe and the North Atlantic.
I think this is it: the umbra. Looking aft on our flightpath around maximum obscuration time. #SolarEclipse pic.twitter.com/rYz7UTpHLv
— Samantha Cristoforetti (@AstroSamantha) March 20, 2015
And in 2017, 2020 and 2021, crews captured the moments the moon’s shadow swept across the United States; southern Chile and Argentina; and Antarctica, respectively.
These astronauts were looking down, watching our planet darken, but the exciting research potential of total solar eclipses, says William Stefanov, NASA’s Exploration Science Office’s branch chief, to Smithsonian magazine, comes from observing—with proper protection—the barely visible slice of sun.
The scientific value of eclipses
Throughout history, astronomers have studied solar eclipses to uncover fundamental knowledge about our planet. “If we go back to ancient astronomy, the geometry of solar and lunar eclipses helped us understand that the Earth and moon are round,” Samantha Thompson, a museum curator at the National Air and Space Museum, says to Smithsonian magazine.
In modern times, however, it’s the sun’s corona—the outermost part of the star’s atmosphere—that piques astronomers’ interest. The corona is much hotter than the sun’s surface, and this extreme heat produces solar wind, a stream of charged particles that emanate from the star. Data from the corona offer clues about this process, as well as the sun’s magnetic activity, surface and interior.
“If we can better understand how the corona works, that helps us understand how space weather and big solar flares might affect things like satellites in orbit, or the International Space Station, or… Earth’s surface,” Stefanov says.
Under normal conditions, it’s difficult to take clean readings of the corona. The sun’s glare usually outshines its dimmer edges, and space-based satellites outfitted with coronagraphs, instruments that block direct sunlight to better view the spectral wisps, are susceptible to light diffraction, Stefanov says.
A total solar eclipse, in theory, would be one of the best times for space-borne astronauts to distinctly observe the sun’s outer atmosphere, when the moon naturally blocks out the rest of the star. But, says Levasseur, due to the arrangement of windows on the space station, its crew won’t be able to observe the corona, even if the station’s orbit were to directly line up with the path of totality. “It’s really a matter of tools and circumstances rather than the desire or intent to view an eclipse,” she says.
However, the current crew might still be able to catch the station’s signature overhead view of the Earth as it becomes darkened by shadow in April, when a solar eclipse will pass over North America.
April’s upcoming solar eclipse
Ahead of the April 8 total solar eclipse, ISS astronauts—whom Stefanov is in contact with and helps train before they leave Earth—are excitedly preparing to become part of the lucky few who get to experience such an event from space.
The four astronauts in SpaceX’s Crew-8 arrived at the station this month, joining the remaining members of the Expedition 71 team, and they will be on board on April 8. However, the station’s exact orbital path has yet to be determined, per Space.com’s Elizabeth Howell. Fortunately, early calculations predict that the orbit will line up well to enable the crew to witness the path of totality, says Stefanov.
“It’s extremely likely that the crew will be in a position to see the moon’s shadow,” he says. “It’s an exciting event from both the standpoint of people on the ground and also those in space.”