Pluto’s Unique Moons! (Synopsis)

“Movin’ right along.
You take it, you know best.
Hey, I’ve never seen the Sun come up in the West?” -
The Muppet Movie

Few things in this world are as regular as sunrise and sunset. With the application of a little physics, you can predict exactly where and when the sun will rise or set from any location on Earth. Thus far, every world in our Solar System -- planet, moon and asteroid -- has had the exact same experience as us.

Image credit: NASA Ames / Dana Berry, of the LADEE spacecraft. Image credit: NASA Ames / Dana Berry, of the LADEE spacecraft.

But out in the Kuiper belt, Pluto is different. The only known world in the Solar System where a significant fraction of the system's mass is not in a single component, the outer moons of the Pluto-Charon system provide a unique environment to study how planets might behave in orbit around binary stars.

Image credit: NASA/JPL-Caltech/T. Pyle. Image credit: NASA/JPL-Caltech/T. Pyle.

The amazing takeaway? The rotational part of the orbit is chaotic; the worlds tumble, and hence sunrises and sunsets are no longer predictable. Go get the whole story over at Medium.

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Nice Work in getting this out so quickly! The press conference announcing this discovery to the world happened less than 6 hours ago.

Ha, I was going to write about something else today... but then this happened. So, this story wins!

The thing about this discovery that I find so amazing is that the moons are so small that they resolve to a single pixel. There are enhanced images, artists renderings, computer models, etc, but the data coming back on each of these moons is essentially a single number from 0-255.

That over a period of observation they could get a series of numbers that read 137,137,138 instead of 137,138,137 and deduce that Tatooine would be more like Westeros is quite incredible. It just goes to show how much we have yet to figure out.

Interesting that systems like this seem stable for billions of years (presumably). Given that (from memory) Eris has a moon as well, is there some part of the formation process for these bodies where we expect to find moons?

There is also the implication that a Earthlike planet around a double star might rotate chaotically, which is actually a good thing (compared to tidal locking, anyway)

By Andrew Dodds (not verified) on 04 Jun 2015 #permalink

@Denier: Actually, the usual sensor hardware & FITS file format usually give at least 16-bit values, so it's 0–65,535, giving rather more information than that.

By Randy Owens (not verified) on 06 Jun 2015 #permalink

"Nix and Hydra, the two largest outer moons, are now close enough to New Horizons that the spacecraft can track how these bodies move in orbit."
But not (currently) how they rotate. So how do we know that "The rotational part of the orbit is chaotic" ?

Because the forces will be such as to make it so, Ichigo.

Irregular objects, orbitals close together, inevitably chaotic on a short timescale.

The New Horizon's team has taken the much appreciated approach of releasing images within 48 hour of receiving it.

The images are unprocessed and nowhere near the marketing grade images the public usually sees on and other places, but there are some very enthusiastic and talented people on the internet who are able to work with the raw images.

The latest images are good enough that we're starting to see albedo variations on Charon.

Not sure if anyone else is following this, but New Horizon's main computer just crashed with just 10 days before closes approach. Mission Control has reestablished contact with the probe, which is now running in safe mode on the back-up computer. At this point they're voicing optimism, but even in the best case scenario there will be no science collected in the next 2-3 days.

It's better now. Better, they know what went wrong.