The trouble is that different groups within the planetary community what the term "planet" (meaning "major planet") for different purposes. Geologists are interested in objects large enough to possess interesting geology. (Size is only part of the story there, actually. Moons of the outer solar system are often more geologically active than, say, Mercury...) Dynamicists care more about the orbits and how the bodies effect other objects. Or, in other circumstances, how they formed. And so forth. It's a subtle thing that took me about two years into grad school to even notice. When I did, the whole debate suddenly took on a different shape, though. In some ways, we are better off *not* rigidly defining the term and letting each subcommunity have it's own nuance.
No. Minor planet != Major planet. The term "planet" when used colloquially is used to mean "major planet". But that's not, in fact, the definition used by astronomers.
"The asteroids in the asteroid belt orbit the sun, and nobody calls them planets."
Not true. Astronomers call them minor planets all the time. That's why the outfit that's charged with tracking all of them is called the "Minor planet center", after all.
A planet is technically any natural object that orbits the Sun. (Let's leave extrasolar planets out of this for the moment, for simplicity.) The Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune are planets. So are Pluto, all of the comets, KBOs, and asteroids.
The difference between the first list and the second (putting Pluto where you wish) is the first are "major" planets and the latter are "minor" planets. So, yes, all KBOs are, by definition, planets.
Now, can you be a major planet and a KBO? Currently, Pluto is both. So there is nothing technically to prevent this. However, whether Pluto *belongs* there is another question.
While I agree with your sentiment whole-hearedly, I feel the need to note that light-speed is not the limit to this problem. The object in question is about 100 AU away, so it takes around 830 minutes for light from it to reach us. While that's a long work-day (or a long flight), that's not really a long time as far as slowing research down.
What does slow things down is that the object mmmmmooooovvvveeessss vvvvveeeeerrrrrryyyyyyy sssssllllooooowwwwllllyyyyy. So getting an orbit determined takes a lot of patience since you need the target to move significantly between observations.
Eccentricity and inclination of orbit. The fact that it the only planet that's totally orbitally bound to another planet via a resonance. (There are some weak effects elsewhere, but nothing like this.) It's the only planet that's tidally locked to it's satellite. It's the only planet that does not fit into either the jovian or terrestrial categories.
I could probably remember more, but I'm tired so I think I'll sleep now instead;-)
It's not just teaching about the solar system, it's thinking about it. From my perspective (a career astronomer), getting the nomenclature right isn't just a minor detail. It facilitates clear communication (having to say "the planets, except Pluto," constantly is a pain so it often gets dropped... and then confusion occurs). And it facilitates clear *thinking*. Having all the bits mentally binned in the best possible category (regardless of history) makes seeing patterns a lot easier.
We're talking about dozens, if not hundreds, of reels of tapes. And people who do have jobs that they have to do. So asking them to volunteer their free time to archive the data is a bit much to ask. (Especially when you consider that the typical scientist works well over 40 hours a week to begin with.)
It isn't that the people didn't want the tapes converted. It's that they just couldn't make it happen with the budgets and time that they had.
Except that most of the useful data from the missions have been saved in other formats by now. I can go to the planetary data system and pull up a lot of Pioneer data right now if I wanted to.
Not every data bit is equally valuable. In this case, the data was probably not originally considered very interesting so wasn't moved at the time. The fact that NASA hasn't copied the data already suggests to me that people near research didn't think that that data would be very helpful in the first place. So while I wish that they'd transfered the data long ago and I applaude the Planetary Society, I am not convinced that this is a horrible failing on NASA's part.
In fact, after a lengthy (around 50 pages) analysis, the team that was looking into the anomoly could not find any source for it. But they also concluded the paper by saying that they suspected the anomoly to be something on the spacecraft and not some new physics.
And while other spacecraft haven't shown this effect (because they have used their thrusters too much), there was a nice paper about a year ago that suggests that the comets we see do *not* show the anomoly, either. So it's not gravitational in nature, most likely,
Because thee are probably hundreds of tapes of data that would take weeks to read and transfer. You have to pay someone to do this, as well as pay someone to maintain the machine in the interm. Neither of which is cheap. Particularly for a mission whose funding has long since turned to dust.
At my lab in grad school we had some Voyager tapes that were only readable by one type of (obsolete) machine. We always wanted to get rid of the machine because it was taking up a ton of space and was a bitch to keep working. But getting the people reasonsible to copy the data to a new format was an uphill battle because there was no money to pay someone (even a student) to do it.
I'm not saying that this is the way things should be or that priorities have been well-set, here. But the economic reality is that it's not as simple as you think.
The one thing you need to do to cinch that argument is show that the tax revenue that is lost to piracy is more than the cost of fighting that piracy. If not, the money is being wasted and could go to fund health care, roads, etc.
I have no idea which way the balance comes out, but it is something I want to see before accepting your case completely. So I'm not saying you're wrong, just that I need more data.
Geosynchronous orbit is unstable due to tidal forces. The tides raised by a satellite (or space elevator anchor) are small and would take millions of years to have a significant effect. Even the young Moon wasn't driven from the geosynchrous orbit on a timescale of years of tens of years. (It was more like tens of thousands. And it induced a much larger tidal bulge on the Earth then and the Earth spun much more rapidly.) So the time needed for a spacecraft to drift from geosynchronous orbit is long.
Now, if you had done your research you'd know that the Lagrange points (L1, L2, and L3. And, under some conditions, L4 and L5.) are unstable over much shorter timescales, more like an orbit of the secondary body. (We once had to calculate the time it would take for a spacecraft to crash into Io when it was displaced from the Io-Jupiter L1 point by 1 meter. The time is about 1 orbit, or around 42 hours in that case.)
Now, it's time for a quick check on something: how does the planet's rotation pull you back outward if you move inside of a stable orbit? (L1 or geosynchronous.) I see a body that moves forward ahead of the anchor point before tension tugs back on it. The tension provides a torque alright, but one that is decreasing the angular momentum of our mass, not increasing it. That should result in amplifying the problem, not fixing it. This is exactly what makes the geosynchronous orbit unstable in the first place, with a tether replacing gravity from a tidal bulge.
Actually, "most orbits" was a bit glib of me. But because it's *fewer* orbits than most. It's the lowest energy ones, as you and I both point out. (I thought it should have been clear when I pointed out that you'd need more fuel to move away from the L1/L2 entry points to the near-Earth system. Sorry if it wasn't.)
The L1 and L2 points aren't *stable*, so it's not clear to me a priori that space elevators to those points from the Moon would work out so well.
Except that they're not where the accelerations cancel. If they were, then there would be exactly one such point.
There is also the frame-force due to the orbit (if you want to track so that the system appears static). That allows for the extra points.
Also, the L4/L5 points are only stable of the mass ratio of the primary to the secondary exceeds a specific value. (About 10:1, as I recall. I could look it up, but.. well, I'm lazy and no one actually cares, I'm guessing.)
That's not totally true. Depending on how much fuel you care to burn off, there *are* chokepoints. Like the Earth-Sun L1 and L2 points. Most orbits entering or leaving the near-Earth region pass through (or near) one of those, unless you're willing to blow fair bit of extra fuel to get out.
Of course, both points are also unstable, so you'd have to use fuel to keep a base there.
I am an astronomer... and you appear to be mostly right. Which of course means that I'm about to nitpick.
First, "Consequently, the Moon appears in its most southerly position, and it appears to 'hang' lower in the sky than during winter months for viewers in the Northern hemisphere (this effect is reversed for Southern hemisphere viewers)."
It's true that the seasons move the location of the ecliptic (the Sun's annual path across the sky) and thus the Moon at night is further south when the Sun is further north. However, there's another effect at play here: the Moon has an inclined orbit (relative to the ecliptic). So depending on where you are in that cycle (it's 17.5 years long, if I recall right), the Moon's position above or below the ecliptic adds to or subtracts from the ecliptics north-south changes.
So it's not so much the timing relative to the solstice (the odds of the solstice being on a day with an effectively-full moon are at least about 1/9, after all), it's about the precession of the lunar nodes.
Also, the Moon is squashed near the horizon, not stretched tall. I have a great photo of this somewhere, but I seem to have lost it in my last move.
Yeah, I was wondering the same thing. It's a poorly written article.
CNN claims that they don't know what has happened to the spacecraft. The Russians say it crashed, but the controllers in Pascadena say it's alive. If they're really getting signals, I believe the latter until the Russians can find the debris.
Microsoft (to trot out the obvious and tired example) makes a killing in the software market, but I don't trust their opinions of Linux.
And you can't read that much about knowledge into how much money a company makes. Profit is as much an art of marketing and keeping costs down as it is making a quality product. If quality equated with profit directly, we'd all be using Apple or IBM machines and no one would have Windows. (And McDonalds would be out of business long since and no one would know who "Britney Spears" is.)
I'll take it one step further: I'm not sure that the statistics are really even meaningful, statistically speaking. (That sentence hurt my brain, and I *wrote* it. Ouch.)
You really need to know how many jobs they binned people in to and how many couples ended up in each bin. If you only have a few dozen per job, then you could easily have a standard error that includes the points described. (Also, I'd want to see how the ratios of boys to girls came out for all of the other job-bins. Are the reported measurements actually egregious, or just the most extreme examples from a continuous distribution?)
There will be angular momentum exchange: the inner edge is tugging on the moon making the moon's orbit expand, while the outer material is tugging the opposite way making the orbit contract. It's possible for the whole thing to be in steady state, actually. Or the moon (and the gap) could be slowly migrating.
However, the ripples don't build up in time because they have a lot of time to go before they re-encounter the moon. In that time, the particles suffer copious collisions and the ripples tend to damp down again. (This isn't 100% true, at least in all cases. Recent work by my graduate advisor and a former student showed that the ring doesn't necessarily lose memory of the last encounter, although I don't think that that applies here.)
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The trouble is that different groups within the planetary community what the term "planet" (meaning "major planet") for different purposes. Geologists are interested in objects large enough to possess interesting geology. (Size is only part of the story there, actually. Moons of the outer solar system are often more geologically active than, say, Mercury...) Dynamicists care more about the orbits and how the bodies effect other objects. Or, in other circumstances, how they formed. And so forth. It's a subtle thing that took me about two years into grad school to even notice. When I did, the whole debate suddenly took on a different shape, though.
In some ways, we are better off *not* rigidly defining the term and letting each subcommunity have it's own nuance.
No. Minor planet != Major planet.
The term "planet" when used colloquially is used to mean "major planet". But that's not, in fact, the definition used by astronomers.
"The asteroids in the asteroid belt orbit the sun, and nobody calls them planets."
Not true. Astronomers call them minor planets all the time. That's why the outfit that's charged with tracking all of them is called the "Minor planet center", after all.
A planet is technically any natural object that orbits the Sun. (Let's leave extrasolar planets out of this for the moment, for simplicity.)
The Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune are planets. So are Pluto, all of the comets, KBOs, and asteroids.
The difference between the first list and the second (putting Pluto where you wish) is the first are "major" planets and the latter are "minor" planets. So, yes, all KBOs are, by definition, planets.
Now, can you be a major planet and a KBO? Currently, Pluto is both. So there is nothing technically to prevent this. However, whether Pluto *belongs* there is another question.
While I agree with your sentiment whole-hearedly, I feel the need to note that light-speed is not the limit to this problem. The object in question is about 100 AU away, so it takes around 830 minutes for light from it to reach us. While that's a long work-day (or a long flight), that's not really a long time as far as slowing research down.
What does slow things down is that the object mmmmmooooovvvveeessss vvvvveeeeerrrrrryyyyyyy sssssllllooooowwwwllllyyyyy. So getting an orbit determined takes a lot of patience since you need the target to move significantly between observations.
Eccentricity and inclination of orbit. The fact that it the only planet that's totally orbitally bound to another planet via a resonance. (There are some weak effects elsewhere, but nothing like this.) It's the only planet that's tidally locked to it's satellite. It's the only planet that does not fit into either the jovian or terrestrial categories.
;-)
I could probably remember more, but I'm tired so I think I'll sleep now instead
It's not just teaching about the solar system, it's thinking about it. From my perspective (a career astronomer), getting the nomenclature right isn't just a minor detail. It facilitates clear communication (having to say "the planets, except Pluto," constantly is a pain so it often gets dropped... and then confusion occurs). And it facilitates clear *thinking*. Having all the bits mentally binned in the best possible category (regardless of history) makes seeing patterns a lot easier.
Maybe. But when you perpetually have a half a dozen or more other things that are rush priorities, it's really easy to let it slip.
I mean, how often do you clean behind the couch? (He asks, rhetorically.)
We're talking about dozens, if not hundreds, of reels of tapes. And people who do have jobs that they have to do. So asking them to volunteer their free time to archive the data is a bit much to ask. (Especially when you consider that the typical scientist works well over 40 hours a week to begin with.)
It isn't that the people didn't want the tapes converted. It's that they just couldn't make it happen with the budgets and time that they had.
Except that most of the useful data from the missions have been saved in other formats by now. I can go to the planetary data system and pull up a lot of Pioneer data right now if I wanted to.
Not every data bit is equally valuable. In this case, the data was probably not originally considered very interesting so wasn't moved at the time. The fact that NASA hasn't copied the data already suggests to me that people near research didn't think that that data would be very helpful in the first place. So while I wish that they'd transfered the data long ago and I applaude the Planetary Society, I am not convinced that this is a horrible failing on NASA's part.
In fact, after a lengthy (around 50 pages) analysis, the team that was looking into the anomoly could not find any source for it. But they also concluded the paper by saying that they suspected the anomoly to be something on the spacecraft and not some new physics.
And while other spacecraft haven't shown this effect (because they have used their thrusters too much), there was a nice paper about a year ago that suggests that the comets we see do *not* show the anomoly, either. So it's not gravitational in nature, most likely,
Because thee are probably hundreds of tapes of data that would take weeks to read and transfer. You have to pay someone to do this, as well as pay someone to maintain the machine in the interm. Neither of which is cheap. Particularly for a mission whose funding has long since turned to dust.
At my lab in grad school we had some Voyager tapes that were only readable by one type of (obsolete) machine. We always wanted to get rid of the machine because it was taking up a ton of space and was a bitch to keep working. But getting the people reasonsible to copy the data to a new format was an uphill battle because there was no money to pay someone (even a student) to do it.
I'm not saying that this is the way things should be or that priorities have been well-set, here. But the economic reality is that it's not as simple as you think.
The one thing you need to do to cinch that argument is show that the tax revenue that is lost to piracy is more than the cost of fighting that piracy. If not, the money is being wasted and could go to fund health care, roads, etc.
I have no idea which way the balance comes out, but it is something I want to see before accepting your case completely. So I'm not saying you're wrong, just that I need more data.
Geosynchronous orbit is unstable due to tidal forces. The tides raised by a satellite (or space elevator anchor) are small and would take millions of years to have a significant effect. Even the young Moon wasn't driven from the geosynchrous orbit on a timescale of years of tens of years. (It was more like tens of thousands. And it induced a much larger tidal bulge on the Earth then and the Earth spun much more rapidly.) So the time needed for a spacecraft to drift from geosynchronous orbit is long.
Now, if you had done your research you'd know that the Lagrange points (L1, L2, and L3. And, under some conditions, L4 and L5.) are unstable over much shorter timescales, more like an orbit of the secondary body. (We once had to calculate the time it would take for a spacecraft to crash into Io when it was displaced from the Io-Jupiter L1 point by 1 meter. The time is about 1 orbit, or around 42 hours in that case.)
Now, it's time for a quick check on something: how does the planet's rotation pull you back outward if you move inside of a stable orbit? (L1 or geosynchronous.) I see a body that moves forward ahead of the anchor point before tension tugs back on it. The tension provides a torque alright, but one that is decreasing the angular momentum of our mass, not increasing it. That should result in amplifying the problem, not fixing it. This is exactly what makes the geosynchronous orbit unstable in the first place, with a tether replacing gravity from a tidal bulge.
Actually, "most orbits" was a bit glib of me. But because it's *fewer* orbits than most. It's the lowest energy ones, as you and I both point out. (I thought it should have been clear when I pointed out that you'd need more fuel to move away from the L1/L2 entry points to the near-Earth system. Sorry if it wasn't.)
The L1 and L2 points aren't *stable*, so it's not clear to me a priori that space elevators to those points from the Moon would work out so well.
We're in agreement, then. Why the "actually"?
Except that they're not where the accelerations cancel. If they were, then there would be exactly one such point.
There is also the frame-force due to the orbit (if you want to track so that the system appears static). That allows for the extra points.
Also, the L4/L5 points are only stable of the mass ratio of the primary to the secondary exceeds a specific value. (About 10:1, as I recall. I could look it up, but.. well, I'm lazy and no one actually cares, I'm guessing.)
That's not totally true. Depending on how much fuel you care to burn off, there *are* chokepoints. Like the Earth-Sun L1 and L2 points. Most orbits entering or leaving the near-Earth region pass through (or near) one of those, unless you're willing to blow fair bit of extra fuel to get out.
Of course, both points are also unstable, so you'd have to use fuel to keep a base there.
No, no. The actual moon gets squashed. But the giant dragon that eats the Sun during eclipses. It's a strange thing to do, but you know dragons...
I am an astronomer... and you appear to be mostly right. Which of course means that I'm about to nitpick.
First, "Consequently, the Moon appears in its most southerly position, and it appears to 'hang' lower in the sky than during winter months for viewers in the Northern hemisphere (this effect is reversed for Southern hemisphere viewers)."
It's true that the seasons move the location of the ecliptic (the Sun's annual path across the sky) and thus the Moon at night is further south when the Sun is further north. However, there's another effect at play here: the Moon has an inclined orbit (relative to the ecliptic). So depending on where you are in that cycle (it's 17.5 years long, if I recall right), the Moon's position above or below the ecliptic adds to or subtracts from the ecliptics north-south changes.
So it's not so much the timing relative to the solstice (the odds of the solstice being on a day with an effectively-full moon are at least about 1/9, after all), it's about the precession of the lunar nodes.
Also, the Moon is squashed near the horizon, not stretched tall. I have a great photo of this somewhere, but I seem to have lost it in my last move.
Yeah, I was wondering the same thing. It's a poorly written article.
CNN claims that they don't know what has happened to the spacecraft. The Russians say it crashed, but the controllers in Pascadena say it's alive. If they're really getting signals, I believe the latter until the Russians can find the debris.
Microsoft (to trot out the obvious and tired example) makes a killing in the software market, but I don't trust their opinions of Linux.
And you can't read that much about knowledge into how much money a company makes. Profit is as much an art of marketing and keeping costs down as it is making a quality product. If quality equated with profit directly, we'd all be using Apple or IBM machines and no one would have Windows. (And McDonalds would be out of business long since and no one would know who "Britney Spears" is.)
I'll take it one step further: I'm not sure that the statistics are really even meaningful, statistically speaking. (That sentence hurt my brain, and I *wrote* it. Ouch.)
You really need to know how many jobs they binned people in to and how many couples ended up in each bin. If you only have a few dozen per job, then you could easily have a standard error that includes the points described. (Also, I'd want to see how the ratios of boys to girls came out for all of the other job-bins. Are the reported measurements actually egregious, or just the most extreme examples from a continuous distribution?)
To be fair, this is what I do for my research. It's not necessarily obvious, I just see this kind of thing every day.
There will be angular momentum exchange: the inner edge is tugging on the moon making the moon's orbit expand, while the outer material is tugging the opposite way making the orbit contract. It's possible for the whole thing to be in steady state, actually. Or the moon (and the gap) could be slowly migrating.
However, the ripples don't build up in time because they have a lot of time to go before they re-encounter the moon. In that time, the particles suffer copious collisions and the ripples tend to damp down again. (This isn't 100% true, at least in all cases. Recent work by my graduate advisor and a former student showed that the ring doesn't necessarily lose memory of the last encounter, although I don't think that that applies here.)