---
title: "Meet Hippocamp, “The Moon That Shouldn’t Be There”"
description: "Researchers have finally figured out why Hippocamp, a tiny moon orbiting Neptune, is able to exist despite its close proximity to a much-larger moon."
date: "2019-02-21"
modified: "2019-02-21"
authors:
  - name: "Kristin Houser"
    link: "https://futurism.com/authors/kristin"
url: "https://futurism.com/the-byte/neptune-moon-hippocamp"
categories:
  - "Astronomy"
  - "Moon"
  - "Science & Energy"
  - "Space"
tags:
  - "hippocamp"
  - "moon"
  - "neptune"
  - "the digest"
---

# Meet Hippocamp, “The Moon That Shouldn’t Be There”

![Researchers have finally figured out why Hippocamp, a tiny moon orbiting Neptune, is able to exist despite its close proximity to a much-larger moon.](<https://futurism.com/wp-content/uploads/2019/02/neptune-moon-hippocamp.png>)
*\<em\>Image: NASA, ESA, and J. Olmsted (STScI)\</em\>*

## Moon Boon

In 2013, [scientists discovered](<https://solarsystem.nasa.gov/moons/neptune-moons/s-2004-n1/in-depth/>) a tiny moon orbiting Neptune. They gave it the forgettable name S/2004 N 1, but it soon earned the nickname of "[the moon that shouldn't be there](<https://www.seti.org/press-release/tiny-neptune-moon-spotted-hubble-may-have-broken-larger>)," because its size and placement didn't make sense to astronomers.

Now, a team of planetary scientists has not only given Neptune's 14th moon a more memorable moniker — Hippocamp — but also unraveled some of the mystery surrounding its origin.

## Tiny, but Fast

In a [paper](<https://www.nature.com/articles/s41586-019-0909-9>) published on Wednesday in the journal *Nature*, the researchers shared the results of several years of analysis about Neptune's tiniest moon.

According to their research, Hippocamp is just 20 miles in diameter and a thousandth of the mass of Proteus, the much-larger moon next to it. It also zips around Neptune at a speed of about 20,000 miles an hour, which is 10 times faster than our Moon circles Earth.

The new name, meanwhile, refers to a mythological sea creature that's half-horse and half-fish — fitting for a moon orbiting the planet named after the Roman god of the sea.

## Splinter Satellite

So that's what the researchers learned about Hippocamp, but it doesn't answer the question as to why "the moon that shouldn't be there" *is* there.

The answer, according to the researchers, is that it probably wasn't always.

If Hippocamp was around 4 billion years ago, Proteus would have likely destroyed the smaller moon while clearing its orbit around Neptune. This led the researchers to conclude that Hippocamp likely formed when a chunk of Proteus broke off following a collision with a comet or asteroid.

"This is the first really great example of a moon that got created as a result of an impact," researcher Mark Showalter [told Space.com](<https://www.space.com/neptune-smallest-moon-hippocamp-named.html>).

**READ MORE:** [Tiny Neptune Moon Spotted by Hubble May Have Broken From Larger Moon](<https://www.space.com/neptune-smallest-moon-hippocamp-named.html>) \[SETI Institute\]

***More on the Moon: [New Research: Earth’s Atmosphere Extends Well Beyond the Moon](<https://futurism.com/earth-atmosphere-beyond-moon>)***

### Author social links  
[LinkedIn](<https://www.linkedin.com/in/kristinjhouser>)