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Pluto's 3 Moons and a Probe to Study Them
It doesn't come easy writes "For those of you keeping score, Pluto now officially has three moons, with more possibly to follow. The newfound moons orbit about 27,000 miles (44,000 kilometers) from Pluto, more than twice as far as Charon, Pluto's other satellite. They are 5,000 times dimmer than Charon. The moons were found using the Hubble Space Telescope. For now, Pluto is the only Kuiper Belt object known to have satellites. Some nice images of Pluto and its moons are included in links. Enjoy!" Relatedly IZ Reloaded writes "NASA says the Atlas 5 rocket that will carry the New Horizons Pluto probe has suffered slight damage thanks to Hurricane Wilma. New Scientist reports: "The Atlas 5 rocket stands within a construction hangar at Cape Canaveral Air Force Station on Florida's east coast. As Wilma rolled though the region on 24 October, fierce 122-kilometer-per-hour winds tore holes in the hangar's 83-meter-tall door and caused minor damage to the rocket inside.""
So not official. RTFA. That's no moon....that's a canditate.
For now, Pluto is the only Kuiper Belt object known to have satellites.
My good friend UB313 would have to disagree.
There are actually several known KBOs with moons. Or was the submitter being overly litteral and meant multiple moons?
Unlike what the poster said, Pluto is not the only one with a moon.. html
Various other KBOs do, including Xena :
http://www.planetary.org/news/2005/xena_moon_1003
I hope we have our XK-PLUTO nuclear-powered bombers ready for the Old Ones. Me? I'm going to take a little trip to XK-Masada.
Does anyone else see real photographs?
The Wikipedia is currently exhibiting the best true-color image of Pluto to date:
http://en.wikipedia.org/wiki/Pluto
has really caused us a lot of grief in classifying heavenly bodies and discovering them. Not only does it interfere with scientific terminology, it hampers understanding of average people. We should just kick Pluto out and accept that we have 8 planets, not 9. Everyone would be happier (except Pluto).
A body having at least one moon is very important for astronomers. By observing even a distant moon, you can get a good fix on its orbital dynamics. Knowing its orbital dynamics, you can determine with a good degree of accuracy how massive the body that has the moon is.
There are all sorts of other benefits moons provide, by the way, as far as astronomy goes, from their chemical properties compared to those of the parent, to their diffraction of light from stars behind them.
Having multiple moons isn't as important, but does raise some interesting questions; this discovery should kick off a brand new round of simulations trying to figure out how those things got there, since the assumed method of formation of Charon was a large collision and reformation. I'm guessing that these would have to be captured after the fact, but having such a large moon as Charon would probably make the capture process quite interesting. It should be neat to see the results.
While I'm eager to see the results from New Horizons (yeah, we'll be waiting a long time!), I'm more interested in getting a flier to Titan, such as a helicopter, non-fixed-wing aircraft, fixed-wing aircraft, or derrigible. The second case sounds the most interesting, because it combines both high speed and low energy requirements. You land, recharge from your RTG while doing a surface study, then take off again (fixed wing can't land reliably, and helicopters and blimps are slower). Too bad there are no good Jupiter gravity assists for a while, so it would have to be a small craft, whatever gets sent.
"99 dead duelists of Dios on the wall. 99 dead duelists of Dios! Take one's ring, pass it around..."
Even if you rolled all the rockets we have ever launched, and all the fuel we packed into them, I doubt it they would form a sphere even a single kilometer in diameter.
A Saturn V was about 20 meters in diameter, and about 100 meters tall, more or less. Volume of a cylinder is pi r^2 * length. That would make the volume of a Saturn V about pi * 2500 meters^3.
The volume of a sphere is 3/4 * pi r^3. The volume of a sphere one kilometer in diameter would be pi * 93,750,000 meters^3. That would be volumne of something like the prelaunch volume of 37,000 Saturn Vs. The payload of a rocket is a fraction of the mass of the entire thing. Let's say 1%. Most rockets are much smaller than a Saturn V. Payloads launched into low earth orbits decay within decades, like Mir, or Spacelab.
It wouldn't surprise me if the volume of all the working satellites, and space detritus, that remain in orbit would be less than the prelaunch volume of a single Saturn V.
Nice? The photographs are a bunch of small white dots! Does anyone else see real photographs? I guess he is referring to the "artistic conceptual drawings"
I disagree. For those of us who get excited about these things, they are actually really cool. For anyone who spends much time in front of a telescope, these are quite exciting.
Now, in terms of whether Pluto is a planet or not... It is clear that it did not form from the same planetary disk that spawned the planets from Neptune on in. It does not appear to be made of the same material, nor does it appear to be close to the plane of the ecliptic. Mars's moons are different and were clearly captured as well though probably from the asteroid belt where planetary formation was disrupted by the gravity of Jupiter (though I suspect that our moon was formed along with the earth in the same band-- the fact that the moon is a near perfect sphere, and that it is within a couple degrees of the ecliptic support this hypothesis I think better than the idea that either the moon was ejected from the earth or that it was captured). Pluto as the nearest of the large KBO's provides many opportunities to study issues involving comet formation and even the dynamics which may have brought the precursors of life to our planet.
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"Having multiple moons isn't as important, but does raise some interesting questions;"
Actually, that isn't true. Particularly in the case of Pluto. Multiple moons certainly help refine mass measurements in the general case. In the case of Pluto, Charon is so large (compared with the parent) that you don't GET the mass of Pluto from an orbital period/distance measurement, you get the mass of combined system. (Technically, this is always true. But for most bodies, including all of the planets, the mass of the moon is negledgible.)
Having a couple small moons which are a lot less massive than Pluto should let astronomers finally work out the correct relative masses of Pluto and Charon. Believe it or not, this is not known all that well.
Oops, a lot of this is based on faulty data.
:-)
First, we don't know that all eight planets have cores. The biggest of the lot, Jupiter, is currently an unknown. A new mission is in the works to test precisely this issue, though.
Second, some asteroids DO have cores. And we're pretty certain that many more used to because that's where the metal-rich asteroids came from. (Break-up of larger asteroids which had differentiated.)
Now, I'm not sure what you mean when you say that the "composition is mixed", but I can't seem to make that statement mean anything that's true of the planet's that's not true of Pluto. Pluto has a mixed composition or rock/metal and ices. It also most likely has a core. (Actually, as of last I checked, we're not really sure about the Moon, either. Which really says something.)
The reason that size makes a popular criterion isn't so much that it's easy as that it's feisible. If you require a core as the test, then you pretty much require a spacecraft flyby (or even an orbiter). Which is tricky for a lot of bodies in our solar system and impossible for ones outside of it. As I said, we don't even know if Jupiter has a core, yet.
There is a rumor, which comes from a reliable source, that the IAU stands a good chance of reversing the Pluto decision now. So stay tuned, we might win this yet
1) The impactor, known alternately as Orpheus or Theia, has been modeled to have been about the size of Mars, and to have hit Earth at a very oblique angle. 2) The absolute best evidence we have for the theory is that the moon has essentially no iron core. All the other terrestrial planets do. As it turns out, the comosition of the moon is remarkably similar to that of Earth's mantle (oxygen/silicon). It is theorized that most of Theia's core merged with our own. Earth's mean density is, if I recall, something on the order of 5500 kg/m^3. The moon has a mean density of something like 3300 kg/m^3. If you were to take out the Earth's iron/nickle core and replace it with mantle material, it would have a mean density similar to that of the moon. 3) As an astronomy minor and having taken planetary formation courses, I've never heard anything about carbonaceous chondrite cores forming the basic building blocks of planets. Carbon, counterintuitively, isn't even too abundant on Earth. Or anywhere else for that matter. Or rather, there certainly is a lot of it, but not compared to oxygen, silicon, iron, aluminum, etc. 4) You can't compare the models of planetary formation in the inner solar system to the outer. Not on a 1:1 basis. The outer planets are significantly larger than the inner because they formed past the frost line (about halfway through the asteroid belt). After this line, ice stays in crystalline form, allowing the rocky starts of the other planets to aggregate much more mass, both planetary and gaseous (the rocky core of Jupiter, at least, is probably about 20 times the size of Earth). With this much more mass, they can more easily capture smaller planetismals, which become moons. It would be far, far easier for a Jupiter to capture Luna than for Earth. 5) As alluded to in the beignning of this post, computer simulations have been done on both the capture and impact theories (including many variations of). The impact theory works. The capture does not. 6) That we have plate tectonics, significant ocean basins, etc, could also be construed as evidence for the giant impact theory. Venus has no moons, and there is little evidence that it ever underwent plate tectonics. The same goes for Mars, and I assume Mercury, though I am not sure on the latter. But the most important thing here is #2. That's the smoking gun.
Interesting, what are the setbacks?
Take a look at http://carnegieinstitution.org/news_980917.html
The basic problem is that the iron/silicon ratios of C1 carbonaceous chondrite meteorites matches the composition of the earth, but new data from the Pathfinder is raising doubts as to whether Mars has the same ratios (as previously thought). If this data continues to hold up it means that C1 carbonaceous chondrites may have helped form Earth, but Mars joins Mercury as an inner planet not formed from them. And as we lack sufficient data from Venus to say for sure, a theory which has been the mainstay of 40 years seems somewhat in peril.
The moon and the earth have the same Oxygen isotope ratios, which supports the impact theory.
Indeed it does seem to support that theory over a coformation theory. However, given the way these are calculated, I don't have enough information to comment further (most of these are the 16Oxygen(16O)/17O v. 16O/18O and plotting this as a line. Though it seems to me that regardless of which theory one wants to support, I would expect the rocks to be fairly rich in 16Oxygen, either due to centrigul action or due to reactions with warm ocean water).
Conservation of Angular Momentum would play an important role, so and the direction that the proto-moon blobbed out would be fairly aribitrary, so I would guess it just turned out that the earth ended up with an AM vector pointed at 23.5 degs to the ecliptic.
This is my problem. If angular momentum is being conserved, and if the tilt of the axis is even half of where it is now then one would expect the moon to follow an orbit near the celestian equator at the time it separated. I don't see tidal forces being that great in in these cases. But I could be wrong. Now, tidal forces combined with a maliable proto-moon could account for the spherical shape.
Just some thoughts...
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