The NASA Hubble telescope discovered the tiny twelve-mile moon, marking the first Neptune moon discovery in a decade.
The moon is known for now as S/2004 N1 and its existence is still a unfolding mystery.
In comparison to the other planet’s moons, this one is of miniscule size and is raising questions as to how it could have survived the ‘chaos’ thought to have created Neptune’s other moons.
Archived pictures from 2009 revealed the faint moon. Mark Showalter of the SETI Institute in Mountain, View, California was examining the past images in an effort to study segments of its rings.
Neptune is too far away to see the rings around it and very long-exposure pictures are relied on to study the planet. This tends to blur the orbiting rings because they orbit so fast. What Showalter and his colleagues found was that taking multiple short-exposure pictures was more effective. They developed a technique to digitally reverse the orbits to a simultaneous moment in time. This enabled them to amass numerous photographs on top of each other, revealing the ring details.
Showalter says what he was looking for was in fact great pictures of the arcs. In addition to successfully taking these pictures, he also found a tiny additional dot. Up to 10 images were stacked on top of each other, allowing the moon to show up as “clear as day.”
Showalter repeated the photography process and stacked them in the same way, still finding the moon in the images and moving as now expected.
Accepted theories about chaos and the construction of other moons and planets thereby are being shaken by this new discovery. Naturally, some scientist’s greatest task at hand is to find out just how the small moon could have survived the formation of the other moons.
Triton is Neptune’s largest moon, spanning 2705 kilometers wide. It also orbits ‘backwards’- making its journey in the opposite direction to its parent planet’s spin.
This has led some astronomers to think that Neptune’s gravity netted Triton about 4 billion years ago, destroying miniscule moons already home to Neptune’s gravity.
“The Neptune moons we see today were probably broken up and regenerated after the arrival of Triton,” says Showalter.
This newly discovered mini-moon is roughly 20 kilometers in diameter. Its orbit is almost circular, taking 23 earth hours to fully orbit Neptune. Its path is directly between the outermost moons besides Triton, Proteus, and Larissa. Proteus clocks in with a diameter of around 400 kilometers, and Larissa holds a comfortable 200-kilometer wide diameter.
According to New Scientist, a tiny rock like the new moon would have been engulfed by Proteus or dispersed by interloping asteroids after the system had settled down.
“How you can have a 20-kilometre object around Neptune is a little bit of a puzzle,” says Showalter. “It’s far enough away that its orbit is stable. Once you put it there it will stay there. The question is how did it get there?”
This does seem an imposing questions for the science teams, what is predicted to take the interests of most though, is the more glamorous task of naming this new little moon. Showalter and his team have said they have no names as of yet, and have dubbed it “that little moon” for the moment.
(Feel free to leave any suggestions for the new moon’s name in the comments section below).