We're pretty much up to finding Jupiters and Saturns, I do believe. But there's a bias toward larger, closer planets with radial velocity searches, to be sure. The question is (and this is not easily answered), how biased are we?
And even with a strong bias, you have to consider that this system exists and is close enough to find at all, which is a separate part of the surprise. (This also depends on numbers, though. If there are a billion stars with planets near us, then a 1:1000 chance of catching something with a strong bias toward finding it isn't surprising. If there are only 100, we start to ask questions.)
I see where you're coming from, but I disagree with that analysis. I feel you need to treat each unlikely aspect separately as long as they're not apparently related. The 1 in 10 should only include unusual orbital configurations and not, say, compositions.
That said, I agree that people are jumping the gun. Usually, the problems (if they exist at all) are tiny. The added effects of one (known) characteristic weren't fully considered or something along those lines.
(Of course, it also bears remembering that there's a selection bias in play with these types of planets: close ones are easier to detect.)
That's because the question is irrelevant. The question you need to ask is, "How unlikely is this scenario that I'm seeing now?" From that, you decide how much to worry about your models. There are weird things about every planet, but that doesn't mean that we shouldn't worry about explaining the unrelated weirdnesses elsewhere. If the behavior isn't correlated, you ought not treat them as if they were.
That's because that question is irrelevant. The important question is how unlikely is *this* scenario. Based on that, you decide how much you should worry about seeing it. Just like when a different, probably unrelated, weirdness appears, you worry about that separately. If the weird behaviors aren't correlated, you shouldn't try to treat them as if they are.
Absolutely. However, scientists get nervous when they see something this unlikely, especially with such a small sample of similar systems to date. Often, such weirdness means something else is going on that we didn't consider, so the nervousness is justifiable in the general case.
And in this case, we need not be conclusive to act. We've got a problem that won't wait around, we can't afford to wait for 3-sigma evidence. Even deferring the decision is, itself, a decision that we're making all the time. So really, all we can do is go with the best data available and do what we can.
What field are you in? The confidence you need varies wildly from field to field based on how clean the data intrinsically is and how repeatable the experiment is. For a historical science like climatology, 90% is pretty damn good.
In any case, I actually don't know of any field where you can't publish a result at a lower confidence. Just because you can't be sure that the data support one theory or another doesn't make the data useless. Often, data from many studies come together to make a coherent picture.
For one thing, there is abviously no chance to have a double blind experiment, since we only have one earth. Second, on the timescales we are arguing about, we are trying to extrapolate judgements from a very small data set. The EPA has squashed some internal opinions that went against the common belief, as has been reported on Slashdot (sorry, I could not find the link).
First of all, you need to look up the difference between a historical science and a laboratory science. You seem to be demanding a level of proof that is not and is never available in a historical science. On the other hand, even a double-blind experiment doesn't prove the underlying theory, it's just stronger support than other studies. (And seriously, what does a double-blind study have to do with physical sciences, anyway? They hardly ever are needed, so I'm wondering why you'd cite them here.)
Is the science water-tight? Heck, no. But we're not talking about academics debating the climate history of Venus, here. We're talking about informing some serious decisions we have to make about our future. When your doctor tells you have you a disease, do you want until the treatments options are water-tight and totally understood (hint: none of them is) or do you treat it with is the best available treatment at the time?
If this were JUST about the science, we'd be happy to sit around as the data trickled in and the models got tweaked and argue this for YEARS. But this isn't just about science anymore, this is about making decisions. We don't have the luxury of our usual centuries-long process.
What you're saying is that the "muddy the waters" campaign is working on you, then. Just like the tobacco industry's campaign to hide the known effects of smoking worked for quite a while. (They're using the exact same playbook and even traded favors, as a matter of fact.)
There have been many refutations of the various studies that question the anthropogenic global warming model. They even make it into the news pretty often. Either you're ignoring them or you're not paying very much attention. For example, they rectified the concerns about satellite temperature measurements of sea temperature and in situ measurements about three years ago in a fairly well-publicized story. (Turns out, the satellite data *does* support the AGW model once you account for what they were actually measuring.)
So yes, there is definitely a pretty strong scientific consensus that this is what's happening. Attempts to fund counter-studies (Lindzen, looking at you) and generally question the science constantly doesn't change the science, just your perception of it. Does this mean that AGW is definitely happening? No, of course not. Scientists can be wrong. But if you're making (or voting on) public policy, it behooves you to use the best models available. You wouldn't refuse to treat your cancer because "the doctor might be wrong", would you?
Nope, grandparent was basically right. You form temporary gravitational aggregates and then let tides destroy them on orbital timescales. It's seen in simulations all the time and the various data show strong indications that such structures must exist. (See, for example, the A Ring Azimuthal Brightness Asymmetry.)
Actually, no. Gravity WILL, in effect, pull objects apart thanks to tides. This is what keeps the rings from accreting into a single body, more or less. So gravity, while most simply an attractive force, *can* actual cause repulsion. (Another fine example is the F ring itself, which is shepherded by two moons. The moons push the ring back when it tries to spread toward the moons.)
This is what keeps the rings from accreting, more or less. And collisions are so slow that grinding isn't a *huge* factor, although some amount of re-collection of dust onto macroscopic particles probably helps that significantly.
Sure, the far side is more cratered. And if you set up that dichotomy on the Moon without having it oriented that way, the less-cratered side would probably turn to orient towards Earth, in solar-system timescales. So that orientation may be misleading. What you need to show us is that the excess impacts on the far side have happened since the Late Heavy Bombardment. I don't think that this is the case. (In fact, the Lunar Highlands on the nearside are as heavily cratered as the far side is. This strongly suggests that the nearside wasn't struck less often, it was just resurfaced when the mare formed.)
Why? The orbital mechanics of that aren't obvious to me. If the speed of the impactors was much larger than the escape speed from the Earth, then a physical blocking approach would make sense. But the relative speed of the impactors should in fact be comparable to the escape speed from Earth, so Earth's gravity will make a significant different in the trajectories. In that case, I can see a case for Earth *focusing* impactors on the Moon after they make close passes of Earth.
The amount of solid matter that has fallen into Jupiter since the end of planet formation 4.5 bya is small compared to its mass, I'm pretty certain. And while most things that hit it are comets, most of what makes up comets is water, methane, and ammonia. You can easily mix those into the fluidic bulk of the planet, if I remember right.
Meanwhile, we have NO measurements that really confirm the existence of a core. We have such data for the *other* giant planets, but measurements of Jupiter include a 0-mass core within their error bars, so we can't promise anything. But we will soon with Juno, so stay tuned.
Right you are. Grazier and Newman had a poster at DPS last fall where they traced back where that idea came from. In fact, someone posited it many years ago and then it became assumed that someone had actually shown it was true. The results of G&N's simulations indicate the opposite: Jupiter is taking pot-shots at the Earth.
Except that that's not true. The notion was based originally on speculation by someone and that speculation turned into established "fact" somehow.
Recent computer simulations (Grazier and Newman) show that in fact Jupiter takes more pot-shots at us than it protects us from. This isn't hard to believe, anything that enters its Hill Sphere is much more likely to scatter than to strike the planet.
It's not a vacuum cleaner, it's gravity isn't so powerful as to pull other objects out of orbit per se. Sure, it probably gets hit more than other planets, but that's not that impressive. It fills less of its Hill Sphere than Earth does, so it's more likely to scatter a passing object than absorb it. And a recent study by Grazier and Newman demonstrated that it probably is taking more pot-shots at Earth than it is protecting us.
Did they edit the blurb? It now reads, " and that downloading them off the NPG site is an 'unlawful circumvention of technical measures.'" That seems pretty clear to me. (But maybe that's because when I was in the NPG 4 years ago, I'm pretty sure that they didn't allow photography. I certain didn't take any pictures, I would have I'm sure.)
We have (and will again) flown through the Enceladus plume.
And the spacecraft can't be allowed to die on an orbit that intersects Enceladus's. We don't want to risk contaminating any potential Enceladan environment with terrestrial microbes and plutonium. The End of Mission scenario we're aiming for right now (it hasn't been approved yet) is to plant the spacecraft in the planet. Those last orbits (inside the D ring) will be glorious.
The high gain antenna on Cassini doesn't pack away, it's a solid dish. (Unlike Galileo, then. Also, this one works...) I'm not 100% certain why they made that design choice (way, way before my time), but it has the benefit of being useful as a shield when they plot through potentially hazardous areas, like dusty rings.
And you don't really back up instruments because no one instrument is really vital to the entire mission. If we lost the ability to do IR spectrascopy, it would be quite a blow, sure. But other instruments would go on and get a lot of results anyway. You lose the engine and you're basically done.
(The one exception on Cassini is the imaging science instrument. It has the highest resolution and is regarded as vital for navigating the spacecraft. I'm not certain that they couldn't work around a failure on ISS, but they really, really don't want to. Also, RSS is basically the high gain antenna, as I understand it, so I'm not sure if it's possible to (effectively) lose RSS and still talk to the spacecraft.)
That said, NASA/JPL does everything it can to preserve the instruments because each one *does* contribute valuable and unique science. You don't want to lose any of them, of course. Fortunately, I suspect that protecting them may be a bit easier than the engineering components. The instruments tend to have very few moving parts, for one thing.
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When your funding depends on at least having some reasonably accurate models to show, "nervous" seems like the right word. :-)
We're pretty much up to finding Jupiters and Saturns, I do believe. But there's a bias toward larger, closer planets with radial velocity searches, to be sure. The question is (and this is not easily answered), how biased are we?
And even with a strong bias, you have to consider that this system exists and is close enough to find at all, which is a separate part of the surprise. (This also depends on numbers, though. If there are a billion stars with planets near us, then a 1:1000 chance of catching something with a strong bias toward finding it isn't surprising. If there are only 100, we start to ask questions.)
I see where you're coming from, but I disagree with that analysis. I feel you need to treat each unlikely aspect separately as long as they're not apparently related. The 1 in 10 should only include unusual orbital configurations and not, say, compositions.
That said, I agree that people are jumping the gun. Usually, the problems (if they exist at all) are tiny. The added effects of one (known) characteristic weren't fully considered or something along those lines.
(Of course, it also bears remembering that there's a selection bias in play with these types of planets: close ones are easier to detect.)
That's because the question is irrelevant. The question you need to ask is, "How unlikely is this scenario that I'm seeing now?" From that, you decide how much to worry about your models. There are weird things about every planet, but that doesn't mean that we shouldn't worry about explaining the unrelated weirdnesses elsewhere. If the behavior isn't correlated, you ought not treat them as if they were.
That's because that question is irrelevant. The important question is how unlikely is *this* scenario. Based on that, you decide how much you should worry about seeing it. Just like when a different, probably unrelated, weirdness appears, you worry about that separately. If the weird behaviors aren't correlated, you shouldn't try to treat them as if they are.
Absolutely. However, scientists get nervous when they see something this unlikely, especially with such a small sample of similar systems to date. Often, such weirdness means something else is going on that we didn't consider, so the nervousness is justifiable in the general case.
Sure, but you need not be conclusive to publish.
And in this case, we need not be conclusive to act. We've got a problem that won't wait around, we can't afford to wait for 3-sigma evidence. Even deferring the decision is, itself, a decision that we're making all the time. So really, all we can do is go with the best data available and do what we can.
What field are you in? The confidence you need varies wildly from field to field based on how clean the data intrinsically is and how repeatable the experiment is. For a historical science like climatology, 90% is pretty damn good.
In any case, I actually don't know of any field where you can't publish a result at a lower confidence. Just because you can't be sure that the data support one theory or another doesn't make the data useless. Often, data from many studies come together to make a coherent picture.
For one thing, there is abviously no chance to have a double blind experiment, since we only have one earth. Second, on the timescales we are arguing about, we are trying to extrapolate judgements from a very small data set. The EPA has squashed some internal opinions that went against the common belief, as has been reported on Slashdot (sorry, I could not find the link).
First of all, you need to look up the difference between a historical science and a laboratory science. You seem to be demanding a level of proof that is not and is never available in a historical science. On the other hand, even a double-blind experiment doesn't prove the underlying theory, it's just stronger support than other studies. (And seriously, what does a double-blind study have to do with physical sciences, anyway? They hardly ever are needed, so I'm wondering why you'd cite them here.)
Is the science water-tight? Heck, no. But we're not talking about academics debating the climate history of Venus, here. We're talking about informing some serious decisions we have to make about our future. When your doctor tells you have you a disease, do you want until the treatments options are water-tight and totally understood (hint: none of them is) or do you treat it with is the best available treatment at the time?
If this were JUST about the science, we'd be happy to sit around as the data trickled in and the models got tweaked and argue this for YEARS. But this isn't just about science anymore, this is about making decisions. We don't have the luxury of our usual centuries-long process.
What you're saying is that the "muddy the waters" campaign is working on you, then. Just like the tobacco industry's campaign to hide the known effects of smoking worked for quite a while. (They're using the exact same playbook and even traded favors, as a matter of fact.)
There have been many refutations of the various studies that question the anthropogenic global warming model. They even make it into the news pretty often. Either you're ignoring them or you're not paying very much attention. For example, they rectified the concerns about satellite temperature measurements of sea temperature and in situ measurements about three years ago in a fairly well-publicized story. (Turns out, the satellite data *does* support the AGW model once you account for what they were actually measuring.)
So yes, there is definitely a pretty strong scientific consensus that this is what's happening. Attempts to fund counter-studies (Lindzen, looking at you) and generally question the science constantly doesn't change the science, just your perception of it. Does this mean that AGW is definitely happening? No, of course not. Scientists can be wrong. But if you're making (or voting on) public policy, it behooves you to use the best models available. You wouldn't refuse to treat your cancer because "the doctor might be wrong", would you?
That's because it's the original source.
Nope, grandparent was basically right. You form temporary gravitational aggregates and then let tides destroy them on orbital timescales. It's seen in simulations all the time and the various data show strong indications that such structures must exist. (See, for example, the A Ring Azimuthal Brightness Asymmetry.)
Actually, no. Gravity WILL, in effect, pull objects apart thanks to tides. This is what keeps the rings from accreting into a single body, more or less. So gravity, while most simply an attractive force, *can* actual cause repulsion. (Another fine example is the F ring itself, which is shepherded by two moons. The moons push the ring back when it tries to spread toward the moons.)
This is what keeps the rings from accreting, more or less. And collisions are so slow that grinding isn't a *huge* factor, although some amount of re-collection of dust onto macroscopic particles probably helps that significantly.
Sure, the far side is more cratered. And if you set up that dichotomy on the Moon without having it oriented that way, the less-cratered side would probably turn to orient towards Earth, in solar-system timescales. So that orientation may be misleading. What you need to show us is that the excess impacts on the far side have happened since the Late Heavy Bombardment. I don't think that this is the case. (In fact, the Lunar Highlands on the nearside are as heavily cratered as the far side is. This strongly suggests that the nearside wasn't struck less often, it was just resurfaced when the mare formed.)
Why? The orbital mechanics of that aren't obvious to me. If the speed of the impactors was much larger than the escape speed from the Earth, then a physical blocking approach would make sense. But the relative speed of the impactors should in fact be comparable to the escape speed from Earth, so Earth's gravity will make a significant different in the trajectories. In that case, I can see a case for Earth *focusing* impactors on the Moon after they make close passes of Earth.
The amount of solid matter that has fallen into Jupiter since the end of planet formation 4.5 bya is small compared to its mass, I'm pretty certain. And while most things that hit it are comets, most of what makes up comets is water, methane, and ammonia. You can easily mix those into the fluidic bulk of the planet, if I remember right.
Meanwhile, we have NO measurements that really confirm the existence of a core. We have such data for the *other* giant planets, but measurements of Jupiter include a 0-mass core within their error bars, so we can't promise anything. But we will soon with Juno, so stay tuned.
Right you are. Grazier and Newman had a poster at DPS last fall where they traced back where that idea came from. In fact, someone posited it many years ago and then it became assumed that someone had actually shown it was true. The results of G&N's simulations indicate the opposite: Jupiter is taking pot-shots at the Earth.
Except that that's not true. The notion was based originally on speculation by someone and that speculation turned into established "fact" somehow.
Recent computer simulations (Grazier and Newman) show that in fact Jupiter takes more pot-shots at us than it protects us from. This isn't hard to believe, anything that enters its Hill Sphere is much more likely to scatter than to strike the planet.
It's not a vacuum cleaner, it's gravity isn't so powerful as to pull other objects out of orbit per se. Sure, it probably gets hit more than other planets, but that's not that impressive. It fills less of its Hill Sphere than Earth does, so it's more likely to scatter a passing object than absorb it. And a recent study by Grazier and Newman demonstrated that it probably is taking more pot-shots at Earth than it is protecting us.
Did they edit the blurb? It now reads, " and that downloading them off the NPG site is an 'unlawful circumvention of technical measures.'" That seems pretty clear to me. (But maybe that's because when I was in the NPG 4 years ago, I'm pretty sure that they didn't allow photography. I certain didn't take any pictures, I would have I'm sure.)
I must have missed something: how is this legal in the US?
In as much as I'm 99% certain that the National Portrait Gallery doesn't allow photography in the site, I'd say that these are not the user's photos.
Both units of distance and, to within the accuracy of the quantity given, they're equivalent. So... yeah, it's valid.
We have (and will again) flown through the Enceladus plume.
And the spacecraft can't be allowed to die on an orbit that intersects Enceladus's. We don't want to risk contaminating any potential Enceladan environment with terrestrial microbes and plutonium. The End of Mission scenario we're aiming for right now (it hasn't been approved yet) is to plant the spacecraft in the planet. Those last orbits (inside the D ring) will be glorious.
The high gain antenna on Cassini doesn't pack away, it's a solid dish. (Unlike Galileo, then. Also, this one works...) I'm not 100% certain why they made that design choice (way, way before my time), but it has the benefit of being useful as a shield when they plot through potentially hazardous areas, like dusty rings.
And you don't really back up instruments because no one instrument is really vital to the entire mission. If we lost the ability to do IR spectrascopy, it would be quite a blow, sure. But other instruments would go on and get a lot of results anyway. You lose the engine and you're basically done.
(The one exception on Cassini is the imaging science instrument. It has the highest resolution and is regarded as vital for navigating the spacecraft. I'm not certain that they couldn't work around a failure on ISS, but they really, really don't want to. Also, RSS is basically the high gain antenna, as I understand it, so I'm not sure if it's possible to (effectively) lose RSS and still talk to the spacecraft.)
That said, NASA/JPL does everything it can to preserve the instruments because each one *does* contribute valuable and unique science. You don't want to lose any of them, of course. Fortunately, I suspect that protecting them may be a bit easier than the engineering components. The instruments tend to have very few moving parts, for one thing.