Neptune’s smallest moon no longer has to go by its previous names of “Neptune XIV” and “S/2004 N1” as it’s now officially known as “Hippocamp”. A team that was led by Mark Showalter of the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California, confirmed the existence of the small moon back in 2013 after studying photographs that were captured by NASA’s Hubble Space Telescope from 2004 to 2009.
Studies showed that the moon is located approximately 65,400 miles from Neptune and it takes around 23 hours to complete one full orbit. To better understand the proximity of Hippocamp to Neptune, our own moon orbits Earth at a distance averaging 239,000 miles.
Out of Neptune’s 14 known moons, Hippocamp is the smallest, as it was thought to have a diameter of no more than 12 miles. However, a new study suggests that it may be slightly larger with a diameter of around 21 miles. That would make it around the same size as the distant object, Ultima Thule. It’s hard to imagine a moon that tiny, as our own moon measures 2,160 miles wide.
As for its name, Hippocamp is a fish-tailed, horse-headed creature in Greek mythology, adding to the Greco-Roman mythology and the sea for the names of the Neptune system. In addition, the name Neptune means the Roman God of the sea which is comparable to the Greek Poseidon.
It’s incredible how the researchers found the small moon in the first place. They took eight five-minute Hubble exposures in sequence of the Neptune system and then they readjusted the pixels in order to stack the photographs on top of each other and that’s how they discovered the tiny moon. “We came really close to missing it entirely,” Showalter said, “It’s too faint to see in a single Hubble [exposure].” The team also used transformation-stacking to locate another one of Neptune’s moons called Naiad which hadn’t been seen since 1989.
Hippocamp is located in the same area as the six moons that were discovered by NASA’s Voyager 2 spacecraft in 1989 and it’s only 7,450 miles interior to Proteus which is the outermost and biggest of the six moons, measuring at 260 miles wide.
It is thought that Hippocamp was more than likely located next to Proteus around 4 billion years ago. In fact, Showalter and his colleagues believe that Hippocamp is younger than Proteus and that perhaps it was created from pieces that were sent into space after the larger moon collided with a comet. It could even be connected to the Pharos Crater that’s located on Proteus from a once huge impact. “This is the first really great example of a moon that got created as a result of an impact,” Showalter suggested.