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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)."
Four moons means it gets to be called a planet.
Astronomers using the Hubble Space Telescope discovered a fourth moon orbiting the icy rock Pluto.
There.. FTFY ;o)
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.
Depending on how you count, it may be more accurate to say "rocky ice". By volume, Pluto has more ice than rock. (By mass, it is indeed an icy rock.)
Astronomers using the Hubble Space Telescope discovered a fourth moon orbiting the icy rocky thing we call Pluto.
There... FTFY :D
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Eris might not be that big after all. The first estimation of its size were made according to its mass, but it seems that this dwarf planet could have a higher density than Pluto.
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.
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Well, the current definition of being spherical and clearing its local neighbourhood (and being in orbit of the star, not another planet), is a pretty good one I think anyway.
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.
It pays to be obvious, especially if you have a reputation for being subtle.
The BBC has a write up that says the other 2 moons were discovered using the Hubble in 2005 at the beginning of the 6th paragraph.
Time to offend someone
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.
All orbiting objects orbit around a non-fixed barycenter. The only factors determining if that center is inside or outside one of the planets is the ratio of masses of an object pair, the distance between them and the radius of the more massive object.
I assume you mean "if I have consistent standards..." since that seems to be the most common argument.
It boils down to how many planets do you want to have in the solar system. Most honest attempts at a scientific definition that includes Pluto also include a handful of other known bodies. That's fine, 8 planets, 9 planets, 14 planets... who cares right? The problem is that modern theory predicts dozens of Pluto-like bodies in the outer solar system, and having 70+ planets listed is seen as extremely awkward, especially when only a handful of them would be scientifically interesting as individual bodies (as opposed to a class of bodies like the predicted objects in the outer Oort cloud would be).
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).
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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.
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Astronomers using the Hubble Space Telescope discovered a fourth moon orbiting the icy rocky thing we call Pluto.
There... FTFY :D
Astronomers using the Hubble Space Telescope discovered a fourth dwarf moon orbiting the icy dwarf planet Pluto.
There... FTFY :D :D
-Actually, would it be a dwarf moon, or a dwarf-planet moon? Or -in this case- both?
I thought there'd be more Mass Effect jokes. Jeeze, people, it's 2011, get over Star Wars!
If you calculate the ratio of the mass of the object to the mass of all the other objects in the same orbit, there is a vast difference between the planets and the dwarf planets. The eight planets have ratios on the order of 10^4 through 10^6, meaning they are much, much more massive than everything else in their orbit combined. The dwarf planets, including Pluto, all have ratios less than one.
Using Pluto's density of 2.03 g/cm^3, I compute (at 21 mile diameter) the moon is 4.2e16 kg.
With a 4.2e16 kg mass and 1.7e4 m radius, I compute an escape velocity of 18 m/s, or 40 miles per hour.
So I suspect you could jump really hard and not come back down, assuming I didn't misplace a decimal point.
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Earth needs more moons!
We should get some.
1. 2.
Yep. I'm pretty comfortable with the idea that our star holds on to more than nine planets. I also think the idea that Pluto isn't a planet is ridiculous, and that any definition that ends up that way is by definition, busted.
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