Enter Hippocamp: Scientists Discover Tiny, City-Sized Moon Hidden in Neptune’s Orbit

A new moon, which astronomers had apparently been missing out on this whole time, has been discovered in our solar system.

Based on telescope images taken in 2013 by NASA’s Hubble Space Telescope that were subjected to the agency’s latest special image analysis techniques, astronomers were able to spot the tiny moon that measures a mere 34 kilometers or about 20 miles in diameter, according to peer-reviewed UK journal Nature.

This is an artist's concept of Neptune's tiny moon Hippocamp. Only 20 miles across, it may actually be a broken-off fragment from a much larger neighboring moon, Proteus! Read the full story: https://t.co/OvX2MvjYzD pic.twitter.com/eQMN7gACD5

— Hubble (@NASAHubble) February 20, 2019

Named Hippocamp after the horse-bodied sea beast from Greek mythology, the earliest known images of the moon were taken in 2004, but at the time scientists were unable to properly sort and catalog the tiny object that behaved in a manner unlike other moons. Even during a relatively close 1989 flyby of Neptune by Voyager 2, Hippocamp wasn’t detectable.

Consisting of extremely dense gas and lying the farthest from the sun, Neptune is one of eight planets in our solar system, with a whopping 14 moons in total – including Hippocamp.

Scientists believe that Hippocamp may not have been born at the same time as Neptune, but was the product of some process that eventually saw the astral body captured by the planet’s strong gravitational pull.

They also believe that the tiny moon could have been the result of an impact between a large comet and a bigger object, such as Neptune’s largest moon, Proteus, which it orbits close to. In such a case, Hippocamp would be the result of fragments knocked away from the neighboring moon.

University of Virginia astronomer Anne J. Verbiscer told Nature:

“Proteus sports an unusually large crater called Pharos — a telltale sign that the moon might have barely escaped destruction by impact … Whenever this impact occurred, it no doubt launched debris into orbit around Neptune.”

The fact that the moon is so tiny suggests “a violent history for the region,” Verbiscer added.

The authors of the study on Hippocamp believe that the latest discovery could unlock the mystery of how other moons were formed, especially if it turns out that this latest find was the result of an impact between a comet and a larger body.

Verbiscer hopes that the imaging technique used by the scientists may also come in handy in future discoveries of tiny moons across outer space, noting:

“Applying the techniques that were used to find (Hippocamp) might result in the detection of other small moons around giant planets, or even planets that orbit distant stars.”