NASA's Hubble Discovers Another Moon Around Pluto

thebchuckster writes "Astronomers using the Hubble Space Telescope discovered a fourth moon orbiting the icy dwarf planet Pluto. The tiny, new satellite – temporarily designated P4 — was uncovered in a Hubble survey searching for rings around the dwarf planet. The new moon is the smallest discovered around Pluto. It has an estimated diameter of 8 to 21 miles (13 to 34 km). By comparison, Charon, Pluto's largest moon, is 648 miles (1,043 km) across, and the other moons, Nix and Hydra, are in the range of 20 to 70 miles in diameter (32 to 113 km)."

Comments

Planet

[Baloroth]

Astronomers using the Hubble Space Telescope discovered a fourth moon orbiting the icy planet Pluto.

There, FTFY :)

More seriously, when did they find the second and third moons? I honestly don't remember ever hearing about them, last I knew Pluto just had Charon. Must be really out of the loop on this.

Re:Planet

[adamjcoon]

Astronomers using the Hubble Space Telescope discovered a fourth moon orbiting the icy rock Pluto.

There.. FTFY ;o)

Re:Planet

[EvanED]

If you count Pluto as a planet, do you count Eris as a planet? (It's bigger than Pluto.) What about Sedna? (Smaller, but not by a whole lot.)

Wikipedia says Nix and Hydra were discovered in 2005 (also by the Hubble team, apparently) and named in 2006.

Re:Planet

[careysub]

Pluto and Charon orbit around a non-fixed barycenter that is actually outside of both Pluto and Charon. Pluto/Charon is really a binary Dwarf Planet with 3 moons. Which, honestly, is fucking awesome.

Absolutely! Further more its physical and orbital characteristics clearly associate it with the recently discovered Kuiper Belt Objects. It is should not be viewed as a "pathetic little planet wannabe" but as the King of the KBOs (Eris would be the Queen).

Re:Planet

[d3ac0n]

Not only that, but as a definition it is empirical and not subjective, like the various "size" based definitions are.

Planet: Any body which has all of the following properties:
1. It's mass has compressed it into a spherical shape.
2. It's primary orbit is around a star
3. It has cleared it's orbit of all other bodies that aren't satellites of itself, Lagrange point bodies, or "twin" satellites of similar mass that it stably co-orbits with where the co-orbital point exists outside either body.

Note the last part there. Not everyone includes this. I include it as it not only allows BOTH Pluto and Charon to be counted as planets, but also takes into account any new extra-solar co-orbiters we may discover in the future.

I mean, wouldn't it be embarrassing to leave that last part out, and then down the road discover a "double earth" planet system orbiting another star and not be able to categorize either earth-sized body as a planet?

Now, if you INSIST on having a "planet / proto-planet" dichotomy, I could accept a fourth definitional point:

4. Must have a gravitational force large enough to hold an atmosphere outside of any solar wind stripping influence.

This addition would still include Pluto, although it might exclude Charon as it has no known atmosphere. However it's lack of atmosphere could also be due to the extreme cold and the fact that most of it's ices are water ices, thus largely non-volatile at those temperatures and unable to "gas off" and create an atmosphere.

Lastly, I have also seen some scientists want to include a 5th definitional point:

5. Has a differentiated structure.

Not sure how Pluto and Charon would stack up against that criterion.

Re:Pluto's Moons

[Ellis D. Tripp]

Hubble will eventually degrade in performance just as it has in the past. Gyros and batteries wear out, electronics get glitchy, etc.

Unfortunately, when it starts to happen again, there won't be anything we can do about it. Without the shuttle, another service mission is impossible. And with Hubble's successor (JWST) hanging by a fraying budgetary thread, there likely will be no replacing it with an improved telescope, either.

We as a country have given up on science, unless it makes immediate profits for megacorporations or helps the military kill people more efficiently in foreign lands.

Re:Pluto's Moons

[the gnat]

Unfortunately, when it starts to happen again, there won't be anything we can do about it. Without the shuttle, another service mission is impossible. And with Hubble's successor (JWST) hanging by a fraying budgetary thread, there likely will be no replacing it with an improved telescope, either.

This has been repeated a number of times, but launching an entirely new Hubble into high orbit (without a shuttle, that is) would be substantially cheaper than maintaining the shuttle program in order to service the existing scope. I hope JWST pulls through, but I don't think NASA should get a blank check from the taxpayers.

We as a country have given up on science, unless it makes immediate profits for megacorporations or helps the military kill people more efficiently in foreign lands.

I'm not a fan of our budget priorities for the last decade, but I can understand why Congress is viewing JWST skeptically. The telescope isn't even supposed to launch until 2017 at the earliest and it's already billions of dollars over budget. Sure, this is a fraction of what we're flushing down the toilet in futile wars, but we're already stuck in those, and they're much more difficult to pull out of than a project that's still in the planning stages.

Except for servicing Hubble - a dubious justification - the shuttle was a terribly inefficient use of money for the science that came out of the program. As far as scientific funding in general is concerned, NASA continues to do great work with remote probes and will be sending another rover to Mars soon. The NIH and NSF managed to avoid major funding cuts in a year when most federal agencies got hit hard, and the DOE Office of Science, which was slated for a huge cut, also survived mostly intact. Speaking as a scientist involved with many of these agencies, I'm thrilled with the outcome.

Mass relay...

[alendit]

I thought there'd be more Mass Effect jokes. Jeeze, people, it's 2011, get over Star Wars!