Wednesday, July 20, 2011

A Fourth Moon for Pluto (and a Celestia File)

Composite image showing the orbital notion of Pluto's moons, including the new P4 (click to embiggen). Image Credit Hubble Space Telescope.

I'm probably the last person to blog this, but a team at the Hubble Space Telescope has discovered a new moon for Pluto.

The tiny moon, charmingly named S/2011 P1 (or P4) at this stage, is somewhere between 13-34 Km in diameter. It orbits between Nix and Hydra, and is probably like then the remnants of a giant impact early in Pluto's history. Interestingly, it was found during a survey looking for rings around Pluto.

The extra moon has re-ignited the "Pluto is a planet" debate, but as asteroids have multiple moons, I don't think this will fly.

You can find more detail and commentary at the Planetary Society Blog and the Bad Astronomer (and Wikipedia). So rather than add more, I'm going to do what I do best, and give you a Celestia file.

Visualisation of P4 in Celestia (click to embiggen).

Pluto, Charon, Nix and Hydra are already in Celestia 1.6 so just copy the data between the lines into a file called newpluto.ssc (or whatever you like), and copy that file into the Celestia extras folder.

The data is quite preliminary (I've just copied a lot from Hydra), and will be updated in the near future, but for the moment the visualization isn't too far off the real thing.

# Newest Moon of Pluto

"Pluto IV:134340 Pluto IV:S/2011 P1" "Sol/Pluto"
Class "minormoon"
Texture "asteroid.jpg" # "spectrally neutral"
Mesh "asteroid.cms"
Radius 17 #upper limit

InfoURL ""

OrbitFrame {
EquatorJ2000 { Center "Sol/Pluto-Charon" }

Epoch 2455740.5 # 2011 June 28
Period 32.1 # mean
SemiMajorAxis 59000 # mean
Eccentricity 0.00 # mean
Inclination 96.362 #Using Hydra
AscendingNode 223.077 #Using Hydra
ArgOfPericenter 45.4 #Using Hydra
MeanLongitude 322.4 #Using Hydra

Albedo 0.18


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