Neptune’s soggiest moon may completely change our hunt for extraterrestrial life
NASA’s Voyager 2 mission sent back evidence of movement on Triton, one of Neptune’s moons, in 1989
Triton appears to have active geysers and an ocean even though it’s one of the coldest bodies in the solar system
If there is an ocean, there might be life on Triton
Traveling to Triton
Look up at the stars. Our galaxy is full of planets and stars and space dust, but is there other life out there? For millennia we’ve been watching, waiting, and hoping for that first contact with friendly beings who share our universe. We’re living in an exciting time because scientists are closer than ever to discovering if anything else is out there.
In 1989, NASA sent Voyager 2 to Neptune. Although Triton, one of Neptune’s 14 moons, wasn’t on Voyager 2’s original agenda, the mission’s engineers changed the flight plan at the last minute to take a closer look at this then-unknown space rock. What they found astounded them then and continues to amaze us still today.
Triton isn’t an ordinary moon. Unlike our familiar sphere of cratered rock, Triton is active and moving. When Voyager 2 passed by, it picked up evidence of spurting geysers and giant waves of unspecified material. Have you ever seen our moon spew space junk? I didn’t think so. As far as we know, Triton is only one of four galactic bodies that move like this (the other three being Earth, Io, and Enceladus).
The story gets even weirder. Not only does Triton feature these unusual geographical features, but this moon also has one of the coldest surface temperatures of any planet or moon out there. The temperature on Triton regularly gets down to -391 degrees Fahrenheit (-235 Celsius); Neptune is close, at an average of -390 degrees Fahrenheit (-200 Celcius). But Neptune, unsurprisingly, doesn’t seem to have any activity like Triton does; it’s freezing. There is some wind atop its icy core, but nothing as crazy as Triton’s very visible movement.
How can Triton help us find aliens?
In addition to the geysers and movement Voyager 2 found on Triton, we also know (with relative certainty, having not actually done the backstroke in it) that Triton is home to an ocean. Not only would that ocean inspire rapid change on the face of the moon, but it also could facilitate life.
Everyone knows that water is essential to life, so the discovery of an ocean on such a far-out body could mean that there is life there, too. If scientists can determine what led an ocean to form on a moon so far from our sun, they might be able to determine the conditions necessary for life. We’ve always thought that water couldn’t occur so far away, but if it can, we might be able to broaden the “habitable zone;” life could be thriving all over the galaxy.
When are we going back to Triton?
With all of this Triton excitement, you’d think we’d be sending a spaceship up there ASAP. And, in NASA terms, we are. NASA is currently planning to propose a mission to visit Neptune and Triton in 2026 in the hopes of confirming the movement Voyager 2 saw and determining its implications for the future of space discovery. Voyager 2 only captured about 40% of Triton’s surface during their flyby, so fingers crossed the 2026 mission sees more, learns more, and shares more. It’s time to find some aliens!
A deeper dive — Related reading from the 101
We’re discovering more about our solar system all the time, and it’s not all about aliens. It’s a vast and mysterious world out there!
You don’t have to look to other planets to find evidence of extraterrestrial life. Sometimes it comes straight down to us, no NASA mission required.