NASA has shared an interview with retired astronaut Bill Anders, who took the iconic Earthrise shot during the Apollo 8 lunar mission in December 1968.

The video (below) landed on NASA’s YouTube channel just before Saturday’s Earth Day, an annual event that seeks to inspire people to work together to protect our precious planet from environmental harm.

Asked to tell the story behind the stunning image of Earth, captured as Anders and fellow crewmembers Frank Borman and James Lovell flew by the moon, the 89-year-old American said he’d been given only a “little bit of photography training” with the modified Hasselblad 500 EL camera that he took to space.

“We were in lunar orbit, upside down and going backwards, so for the first revolutions we didn’t see the Earth and I didn’t really think about that,” Anders said.

“And then we righted ourselves, you know, heads up, and twisted the spacecraft so it was going forward, and while Frank Borman was in the process of doing that, suddenly I saw in the corner of my eye this color. It was shocking.”

Film captured by the crew, shared in Anders’ interview, shows the extraordinary moment when Earth appears over the moon’s horizon. Upon witnessing the stunning view, Anders can be heard saying: “Oh my god, look at that picture over there. There’s the Earth coming up.”

Anders suddenly realizes that it’s a photo opportunity that he doesn’t want to miss, and asks Lovell to pass him a roll of color film “quick.”

The astronaut said he “put the long lens on and started snapping away,” adding that he changed the camera’s settings slightly with each shot in the hope that at least one of the frames would be correctly exposed.

Pondering Earth Day and how the famous photo continues to have an impact, Anders repeats one of his favorite lines about the 1968 space voyage: “We went to the moon to explore the moon, and what we discovered was the Earth,” adding: “[The photo] makes people think, the fragile little ball that we live on.”