Nix – Pluto Moons | Eternal Years of Chaotic Dance

Nix Moon – Basic Information

Origin of Moon Nix

After being discovered as the ninth planet in our solar system, astronomers have always been concerned about Pluto. Even NASA planned a long term mission, New Horizons to reach to Pluto area. The aim was to investigate the planet together with her only known moon Charon. And more Kuiper Belt objects were planned to be the following stations.

Just months before departure of New Horizons Spacecraft, two new Pluto moons have been discovered by Pluto Companion Search Team: Nix and Hydra. Even before the spacecraft arrived to mission target near Pluto, the team located two more moons named Styx and Kerberos.

That was awesome since those discoveries projected New Horzions Team 4 more “new horizons“!

Moon Nix discovery picture
First ever picture of two moons Nix and Hydra in 2005, by Hubble Space Telescope. Source: Hubblesite, Credit: NASA, ESA, H. Weaver (JHU/APL), A. Stern (SwRI), and the HST Pluto Companion Search Team

What Is Moon Nix?

Nix is a Trans Neptunian, irregular sized object. And she is the third biggest satellite of Pluto. Similar to Pluto, she is living mostly in Kuiper belt, with an almost circular orbit around her parental planet. Both rocks are orbiting sun together.

Studying the shape and the structure, astronomers believe this little satellite might be formed after a second collision between two small moons. This collision seems to follow a bigger collision between Pluto and another object similar in size. However, with the amount of data we have about this moon and history of solar system, this is substantially a lucky guess.

Orbit and Rotation

Best way to visualize Nix’s rotation is as follows: Take a giant potato, place it into heavily seething water and watch what happens! Well, density of moon Nix is around 1.37 g/cm³; which means she will naturally sink in fresh water but.. Let’s neglect this for now.

Credit: NASA, ESA, M. Showalter (SETI Inst.), G. Bacon (STScI)

One Nix day is calculated to be about 44 hours in 2015, however this period decreased by 10% right after New Horizons’ calculation. It’s really not worth to sensitively count days over there. That’s why, it will be more wise to use only yearly-based time calculation and lower down expectations about calculating days&nights.

It takes about 25 days for moon Nix to complete her one tour around Pluto System’s gravitational center.

Moon Nix is the third outer and innermost known satellite in Pluto System at the same time. And she orbits around gravitational center of system from 48.694 kilometers away. The orbital inclination is almost zero.

Overview of Pluto Moons in Pluto System. Credit: NASA/JHUAPL/SwRI/Mark Showalter Video produced by AGU

Size and Structure

Being the third biggest satellite of Pluto, moon Nix is 133 million times smaller than Earth.

This tiny moon is shaped almost like a potato, and we can state her basic dimensions as: 49.8 x 33.2 x 31.1kilometers.

For better understanding of size, grab your sharpest hypothetical huge knife and slice her without paring the peel. Make sure this icy potato is already cool enough before slicing. We don’t want to crack it!

Do not try at home!

The inner surface area of the hemisphere will be slightly bigger than Singapore.

Nix has a surface gravity of 1/6.135 of Earth, which makes it quite easy to wander around. Even quite easy to escape from its gravitational effect.

When we talk about planetary bodies and their satellites, we mention about their core, surface and atmosphere. But for small ones like this, mostly there’s not much chance to spell the word atmosphere at all.

And when there’s no proper atmosphere covering, you can not increase the surface temperature. Temperature on Nix surface is about -230ºC.

Surface Features

One more common Pluto fact including together with her moons is the red color.

Similar to surface of Pluto and Charon, existence of methane and formation of tholins is anticipated upon the observable wide red colored area on moon Nix. This are is calculated to be about 18km long.

As well as other Pluto moons, water ice is observed on moon Nix surface too.

On our detailed article regarding moon Charon, we mentioned about formation of tholin layers on north pole of Charon. Scientists believe such formation occurred following an interesting methane transfer process from Pluto to Charon.

Pluto and Charon
Pluto and Charon. Source: NASA

When it comes to Nix moon, we don’t believe that’s the case. Well, Pluto and Charon are tidally locked to each other and have stable rotations. And such transfer looks rational. However we do not observe such dense distributions on specific parts of moon Nix surface.

That’s why, there is a different hypothesis about this red area. Since that zone also looks deeply wounded, a big object might have recently impacted and blended surface material with the composite inner part. And this might have initiated the process of tholin formation.

Nix moon
Best picture of moon Nix by New Horizons. Tholin area seen on south east. If you can call it south east! Source: NASA

Living on Nix

Nix does not seem to be life-friendly for the living organisms we know. With remarkable possibility of a subsurface ocean, planet Pluto itself on the other hand, has a chance to host primitive life. However, we can not claim anything when it comes to other tiny moons.

Nix Moon
There’s nothing to shame for being a tiny moon! Well, that’s only the initial low-resolution view of Nix; via New Horizons Spacecraft. Source: NASA

Nix Moon – Story of Discovery

Nix was discovered in 2005 together with second biggest satellite Hydra by New Horizons Team. The team detected both moons via Hubble Space Telescope. Hal Weaver and Alan Stern were the team leaders.

Existence of those two Pluto moons was verified via the images taken on 15 May and 18 May 2005. The discovery was officially announced on 30 October 2005.

Nix Moon – Naming

IAU did not surprise global astronomy community and named this satellite from Greek Mythology as well. They decided to name this moon as Nyx, which is the Greek goddess of darkness and night.

But there was another object – an asteroid named Nyx. Even Greek mythology has limits! That’s why they decided to switch to Egyptian spelling of the word – Nix – to avoid any confusion.

IAU announced naming on 21 June 2006 together with moon Hydra.

Pluto Moons Nix and Hydra
Pluto moons Nix and Hydra. Source: NASA

Nix in Astrology

Nix, its size, distance to earth, gravitational effect or any other specification has nothing to do with your horoscope, daily life or anything else about your mood. This is common for any satellite, planet or star you can think of.

Astrology means fairy tales.

Astronomy relies on facts; on a thing we named in last few centuries: The Science.


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