10 Hippocamp Moon Facts | Interesting Facts about Tiny Hippocamp

Hippocamp is the smallest moon that orbits the planet Neptune. Not much is known about it, as it has avoided spacecrafts for decades. In fact, we didn’t even know it existed until 2013! Either way, it is an interesting moon, largely due to it’s size. So, let’s look at some Hippocamp facts and learn more about it! 

The tiny moon Hippocamp!

Hippocamp Moon Facts

  1. Hippocamp has a diameter of approximately 20 miles (35 kilometer). This makes it the smallest moon that orbits the planet Neptune. 
  2. It thought that Hippocamp might actually be a piece of another Neptune moon called Proteus. Astronomers think that a collision with a comet billions of years ago may have caused this.
  3. There are only 12,000km between Proteus and Hippocamp, which is why astronomers believe it to be a piece of the larger moon.
  4. There is also another theory that Hippocamp is a stray object from the Kuiper belt that has been caught in Neptune’s gravity.
  5. It’s so small that Hippocamp evaded the spacecraft Voyager 2 that passed Neptune when it was exploring the planet and it’s moons.
  6. The tiny moon orbits Neptune at quite a far distance of 65,420 miles (105,283 km). 
  7. It takes Hippocamp around 23 hours to orbit Neptune fully. To do this, it goes at speeds of over 20,000mph (32,000kmph).
  8. Although most other Neptune were discovered earlier, Hippocamp wasn’t discovered until 2013. It wasn’t named as an official moon until 2019, though.
  9. This moon takes it’s name from the mythological beast, the Hippocampus.
  10. Hippocamp is far too small for it to have an atmosphere like some of the other, larger moons.
  11. Unfortunately, there are no approved missions to go to Neptune, so it is unlikely we will learn much more about Hippocamp in the near future.

Commonly Asked Questions about Hippocamp

When was Hippocamp discovered?

Hippocamp actually wasn’t discovered until July 2013. It was completely missed by the Voyager spacecrafts that are currently in interstellar space, due to it’s small size. However, images from the Hubble Space telescope taken from almost a decade earlier allowed Mark Showalter’s team of astronomers at the SETI institute to discover Hippocamp.


Where did Hippocamp get it’s name?

A Hippocampus in Greek mythology is actually a half horse, half fish hybrid that roams the ocean. It was likely named the Hippocamp because the Hippocampus would have been in Neptune’s control in Roman mythology, as Neptune was the king of the ocean. He had a chariot, with Hippocampi effectively being the horses. A Hippocampus is also the scientific name for a seahorse!

Is the Hippocamp the smallest moon?

Although it is small, Hippocamp still isn’t the smallest moon in our solar system. That title belongs to Deimos, one of the two moons that orbit the planet Mars.


What is Hippocamp made of?

We actually don’t know too much about the composition of Hippocamp. It is thought to consist of silicate rock, with a water ice coating across it’s crust due to the extremely cold temperatures out near Neptune.

How many other moons does Neptune have?

As well as the moon Hippocamp, Neptune also has many other moons. The biggest amongst them is Triton, which is on par with the Earth’s moon for size. There is also Proteus, and Nereid, which is the third largest moon of Neptune.



Overall, we do not know a lot about the tiny moon Hippocamp aside from it’s small size and startling speed that it travels around Neptune. it was completely missed by previous missions into space, and it’s easy to see how when you consider it’s radius. Hopefully you have learned something about Hippocamp in this group of facts about it!


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