- Thank you received: 0
Is the Sun a binary?
- tvanflandern
- Offline
- Platinum Member
Less
More
18 years 3 months ago #4222
by tvanflandern
Replied by tvanflandern on topic Reply from Tom Van Flandern
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by nemesis</i>
<br /><blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">[tvf]: A supernova that close would have wiped out the solar nebula from which the planets formed, and would have made the Sun into a "peculiar" star (in the stellar classification sense of "peculiar").<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">It seems, since you favor the fission model, this would have no relevance. It should not affect fission.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">True, a supernova would not affect planet formation by fission, but the supernova would still turn the Sun from a normal G2 dwarf star into a peculiar star. Your only "out" here would be that the Sun might recover after 4.6 billion years and start to look normal again. We don't know enough stellar evolution theory to be sure how peculiar stars evolve.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I believe you said elsewhere that a nearby supernova would have "wiped out" the solar system planets, if any yet existed.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Certainly not the planets themselves, but all life on them would be killed off by severe gamma radiation.
Moreover, supernova renmants tend to acquire very high speeds through the galaxy as a result of the asymmetry of the explosion. Some of these remnants are speeding along at over 1000 km/s. Escape speed from the solar system at 1000 au is less than 1 km/s, so it would require an oddly symmetric supernova (almost perfectly so) to remain a solar captive.
Looking over all the problems with this nearby supernova scenario, I'd have to rate its plausibility as rather low, but I can't say "impossible". However, some of the other points I made about the Cruttenden model do rate an "impossible" label.
In particular, how do you plan to dodge the pulsar timing argument, which shows that the Sun is not presently accelerating toward any significant nearby mass? A neutron star at 100,000 au would be detected by this method. Combined with the lack of visibility in surveys, the lack of observable gravitational lensing, and the lack of any anomaly that cannot be better explained in some other way, I'd say it was time to give "Nemesis" a rest. The sky is filled with interesting mysteries awaiting innovative thinkers. -|Tom|-
<br /><blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">[tvf]: A supernova that close would have wiped out the solar nebula from which the planets formed, and would have made the Sun into a "peculiar" star (in the stellar classification sense of "peculiar").<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">It seems, since you favor the fission model, this would have no relevance. It should not affect fission.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">True, a supernova would not affect planet formation by fission, but the supernova would still turn the Sun from a normal G2 dwarf star into a peculiar star. Your only "out" here would be that the Sun might recover after 4.6 billion years and start to look normal again. We don't know enough stellar evolution theory to be sure how peculiar stars evolve.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I believe you said elsewhere that a nearby supernova would have "wiped out" the solar system planets, if any yet existed.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Certainly not the planets themselves, but all life on them would be killed off by severe gamma radiation.
Moreover, supernova renmants tend to acquire very high speeds through the galaxy as a result of the asymmetry of the explosion. Some of these remnants are speeding along at over 1000 km/s. Escape speed from the solar system at 1000 au is less than 1 km/s, so it would require an oddly symmetric supernova (almost perfectly so) to remain a solar captive.
Looking over all the problems with this nearby supernova scenario, I'd have to rate its plausibility as rather low, but I can't say "impossible". However, some of the other points I made about the Cruttenden model do rate an "impossible" label.
In particular, how do you plan to dodge the pulsar timing argument, which shows that the Sun is not presently accelerating toward any significant nearby mass? A neutron star at 100,000 au would be detected by this method. Combined with the lack of visibility in surveys, the lack of observable gravitational lensing, and the lack of any anomaly that cannot be better explained in some other way, I'd say it was time to give "Nemesis" a rest. The sky is filled with interesting mysteries awaiting innovative thinkers. -|Tom|-
Please Log in or Create an account to join the conversation.
- MarkVitrone
- Topic Author
- Offline
- Platinum Member
Less
More
- Thank you received: 0
18 years 3 months ago #4224
by MarkVitrone
Replied by MarkVitrone on topic Reply from Mark Vitrone
Now everyone must contribute the national average of $600/credit hour for graduate credits. If you read this thread today, then you were the happy recipient of one credit hour in advanced celestial mechanics. Make checks payable to Mark Vitrone
Yes I am joking
Nemesis,
I think the most compelling argument against the binary system is the observation noted by Tom that the precession is dependant upon the oblateness of the planet. Clearly each planet experiences this because of its own shape, mass, composition, and rotation and not because of another star.
A widget is an invention that fixes your theory, just like PAM keeps eggs from sticking to a frying pan, a widget is something scientists try to use to keep eggs from sticking to their faces.
Mark Vitrone
Yes I am joking
Nemesis,
I think the most compelling argument against the binary system is the observation noted by Tom that the precession is dependant upon the oblateness of the planet. Clearly each planet experiences this because of its own shape, mass, composition, and rotation and not because of another star.
A widget is an invention that fixes your theory, just like PAM keeps eggs from sticking to a frying pan, a widget is something scientists try to use to keep eggs from sticking to their faces.
Mark Vitrone
Please Log in or Create an account to join the conversation.
18 years 3 months ago #9128
by nemesis
Replied by nemesis on topic Reply from
Thanks Mark, that's what I thought you meant by "widget", a fudge factor or unprovable assumption. There are many in Big Bang theory, like inflation, "dark matter", etc. as has been amply discussed on this board. But these are things that could not even in principle be detected, whereas a solar companion could be.
I think the exploded planet hypothesis is interesting and explains many observations. But it has its "widget" too, the explosion of the planets. Nobody has ever observed an exploding planet, and I know that mechanisms have been proposed, but most astronomers and physicists would not accept them. Perhaps massive objects like planets generate energy by some unknown mechanism (Paul LaViolette has proposed this) but that introduces another "widget".
One more thing about the binary idea, we kind of got sidetracked into talking about a collapsed object. I think personally a brown dwarf or "super Jupiter" would be more plausible. There are many very faint solar system objects, like Sedna, being discovered, and undoubtedly many more to come.
I think the exploded planet hypothesis is interesting and explains many observations. But it has its "widget" too, the explosion of the planets. Nobody has ever observed an exploding planet, and I know that mechanisms have been proposed, but most astronomers and physicists would not accept them. Perhaps massive objects like planets generate energy by some unknown mechanism (Paul LaViolette has proposed this) but that introduces another "widget".
One more thing about the binary idea, we kind of got sidetracked into talking about a collapsed object. I think personally a brown dwarf or "super Jupiter" would be more plausible. There are many very faint solar system objects, like Sedna, being discovered, and undoubtedly many more to come.
Please Log in or Create an account to join the conversation.
- tvanflandern
- Offline
- Platinum Member
Less
More
- Thank you received: 0
18 years 3 months ago #9192
by tvanflandern
Replied by tvanflandern on topic Reply from Tom Van Flandern
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by nemesis</i>
<br />But these are things that could not even in principle be detected, whereas a solar companion could be.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">A solar companion has the opposite problem. Much like an elephant in the room, it could not fail to be detected.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I think the exploded planet hypothesis is interesting and explains many observations. But it has its "widget" too, the explosion of the planets. Nobody has ever observed an exploding planet...<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">On the contrary. I have proposed that classical novas, which are explosions of invisible companions orbiting visible stars, are actually planet explosions instead of star explosions for several reasons. (But this thread is not about the EPH, so I'll stick to the qualitative aspects of judging theories here.)
Besides, you don't have to witness an accident to judge that one occurred when you come upon two wrecked, smoking vehicles and a couple of injured drivers. It is similar for the (estimated to be) six planet explosions and several smaller moon explosions in our solar system, dating back to the spectacular "late heavy bombardment" event at 3.9 billion years ago that resurfaced our Moon, among other things. My book lists over 100 lines of evidence indicative of these explosions, found on planets and moons and in comets, asteroids, and meteorites.
Note how this abundance of evidence, all telling the same story and more constantly turning up with every new discovery, contrasts with the solar companion hypothesis, for which there is no evidence at all that does not have a better explanation and no successful predictions.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">... and I know that mechanisms have been proposed, but most astronomers and physicists would not accept them.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">There are three known mechanisms, the best of which also solves the unexplained mystery about how supernova explosions can occur in far less time than the various parts of the pre-explosion star can communicate with one another at the speed of light. "Acceptance" is not a scientific criterion because new ideas often take a generation or two to catch on. However, specific objections are important, and there have been none of those in connection with these explosion mechanisms.
Note that the graviton mechanism, which I classify as the best of the three, did not arise to explain planet explosions. Instead, it came out deductively and inevitably from the Le Sage gravity mechanism that has enjoyed so many successes in other areas. That is why the explosion mechanism is not a widget. It was not devised to keep a theory viable, but was forced on us from unrelated considerations, and happened be to a perfect fit with EPH. Again, contrast with the solar companion model, which has not predicted anything successfully that we did not already know.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I think personally a brown dwarf or "super Jupiter" would be more plausible. There are many very faint solar system objects, like Sedna, being discovered, and undoubtedly many more to come.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">And you can easily hide more Sednas out to great distances. But you cannot hide "super Jupiters" or brown dwarfs at any distance in our solar system because they give off so much heat that they would be the brightest things in the infrared sky.
If I might make a general observation that applies to the majority of bright people trying to make their own contributions to science --
Scientific method teaches us to remain totally detached and objective about our own ideas because experience has shown that our very best inspirations can usually be shot down by some heartless and annoying fact. And without that objectivity, we all tend to find excuses for our pet idea and finds reasons to continue believing in it until it becomes a certainty in our minds. This happens in all areas of human activity. We deceive ourselves.
The "controls" feature of scientific method is the part now frequently ignored because, if adhered to, many popular theories would fall and many "experts" would be left red-faced. But the purpose of controls is precisely to keep us from fooling ourselves. It places barriers between the results of a hypothesis test and our own biases, so that the latter cannot influence the former. That is the only way to keep on productive pathways.
I have taught my own students that you are not ready to do productive, original research until you have shot down at least three of you own finest inspirations. It is a humbling experience, but teaches us how very imporatnt a good protocol with controls is, and helps us home in on hypotheses that can pass tests under such rigorous standards. I highly recommend developing an understanding of this and implementing it in all scientific thinking to everyone reading this. The penalty for doing otherwise is risking wasting a career and a brilliant mind (your own) pursuing unproductive pathways. -|Tom|-
<br />But these are things that could not even in principle be detected, whereas a solar companion could be.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">A solar companion has the opposite problem. Much like an elephant in the room, it could not fail to be detected.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I think the exploded planet hypothesis is interesting and explains many observations. But it has its "widget" too, the explosion of the planets. Nobody has ever observed an exploding planet...<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">On the contrary. I have proposed that classical novas, which are explosions of invisible companions orbiting visible stars, are actually planet explosions instead of star explosions for several reasons. (But this thread is not about the EPH, so I'll stick to the qualitative aspects of judging theories here.)
Besides, you don't have to witness an accident to judge that one occurred when you come upon two wrecked, smoking vehicles and a couple of injured drivers. It is similar for the (estimated to be) six planet explosions and several smaller moon explosions in our solar system, dating back to the spectacular "late heavy bombardment" event at 3.9 billion years ago that resurfaced our Moon, among other things. My book lists over 100 lines of evidence indicative of these explosions, found on planets and moons and in comets, asteroids, and meteorites.
Note how this abundance of evidence, all telling the same story and more constantly turning up with every new discovery, contrasts with the solar companion hypothesis, for which there is no evidence at all that does not have a better explanation and no successful predictions.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">... and I know that mechanisms have been proposed, but most astronomers and physicists would not accept them.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">There are three known mechanisms, the best of which also solves the unexplained mystery about how supernova explosions can occur in far less time than the various parts of the pre-explosion star can communicate with one another at the speed of light. "Acceptance" is not a scientific criterion because new ideas often take a generation or two to catch on. However, specific objections are important, and there have been none of those in connection with these explosion mechanisms.
Note that the graviton mechanism, which I classify as the best of the three, did not arise to explain planet explosions. Instead, it came out deductively and inevitably from the Le Sage gravity mechanism that has enjoyed so many successes in other areas. That is why the explosion mechanism is not a widget. It was not devised to keep a theory viable, but was forced on us from unrelated considerations, and happened be to a perfect fit with EPH. Again, contrast with the solar companion model, which has not predicted anything successfully that we did not already know.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I think personally a brown dwarf or "super Jupiter" would be more plausible. There are many very faint solar system objects, like Sedna, being discovered, and undoubtedly many more to come.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">And you can easily hide more Sednas out to great distances. But you cannot hide "super Jupiters" or brown dwarfs at any distance in our solar system because they give off so much heat that they would be the brightest things in the infrared sky.
If I might make a general observation that applies to the majority of bright people trying to make their own contributions to science --
Scientific method teaches us to remain totally detached and objective about our own ideas because experience has shown that our very best inspirations can usually be shot down by some heartless and annoying fact. And without that objectivity, we all tend to find excuses for our pet idea and finds reasons to continue believing in it until it becomes a certainty in our minds. This happens in all areas of human activity. We deceive ourselves.
The "controls" feature of scientific method is the part now frequently ignored because, if adhered to, many popular theories would fall and many "experts" would be left red-faced. But the purpose of controls is precisely to keep us from fooling ourselves. It places barriers between the results of a hypothesis test and our own biases, so that the latter cannot influence the former. That is the only way to keep on productive pathways.
I have taught my own students that you are not ready to do productive, original research until you have shot down at least three of you own finest inspirations. It is a humbling experience, but teaches us how very imporatnt a good protocol with controls is, and helps us home in on hypotheses that can pass tests under such rigorous standards. I highly recommend developing an understanding of this and implementing it in all scientific thinking to everyone reading this. The penalty for doing otherwise is risking wasting a career and a brilliant mind (your own) pursuing unproductive pathways. -|Tom|-
Please Log in or Create an account to join the conversation.
18 years 2 months ago #9147
by nemesis
Replied by nemesis on topic Reply from
Tom, I went back and reread some of what you had written, and I have a couple more questions.
"Gravitational tugs from a distant star, much like those from other planets, would change Earth's orbit around the Sun, but have
essentially no effect whatever on precession. That is because precession is not caused by inverse square forces acting on its
center of mass, but rather by inverse cube torques acting differently on different parts of the Earth's non-spherical shape. A very distant body, because of that distance, would apply essentially identical forces to every part of the Earth, causing no precession." -TVF
I must be missing something. The precession effect (shift of the fixed stars) would be caused by the rotation of the entire solar system, not gravitational torquing of the Earth's equitorial bulge like lunisolar effects do. And of course nobody claims that such lunisolar effects do not occur. At that distance the torquing effect of a hypothetical binary companion could be ignored completely. The question is, are lunisolar effects alone enough to account for observations? And,
"Other planets have spin axis precession also, but at drastically different rates that depend on the amount of spin flattening and
distance from the Sun of those planets. The unseen companion is supposed to produce the same change for all planets because it is
rotating the whole solar system. But that is contradicted by observations." - TVF
I'd think we couldn't expect to see the effect on the other planets caused by the solar system's rotation from the vantage point of the Earth, since we are all on the same merry-go-round, so to speak. We should see only their local gravitational torquing from spin flattening, etc. We could in principle test the binary hypothesis by placing a camera on the surface of Mars and having it measure the position of the fixed stars at Mars' own vernal equinox for a few orbits. If all we see is Mars' measured local precession of -707" per century, the binary hypothesis is falsified. If extra shifting of the stars is seen, an additional effect is there which needs an explanation. (Don't ask me to ask for funding for this.)
I think I mentioned the seasons regressing through the calender, and you said the calender was set up to track the tropical year so that does not happen. What I intended to say was that today, the winter solstace in the northern hemisphere takes place when the earth is near perigee. Lunisolar precession or "wobbling" of the spin axis indicates that in 12,000 years the solstace will take place near apogee. The calendar will still say late December, and it will be winter, but the seasons in the northern hemisphere may be a little more extreme. On the other hand, if most of the precession effect is from solar rotation around a companion, the solstace will still be near perigee.
Finally, in your discussion of possible planetary explosion mechanisms elsewhere on the site, you state that stars need an ignition mechanism, which could be a fission chain reaction, but "...then dark stars of all masses might exist for which no ignition occurred." Would such a "dark star" be cold as well as dark?
"Gravitational tugs from a distant star, much like those from other planets, would change Earth's orbit around the Sun, but have
essentially no effect whatever on precession. That is because precession is not caused by inverse square forces acting on its
center of mass, but rather by inverse cube torques acting differently on different parts of the Earth's non-spherical shape. A very distant body, because of that distance, would apply essentially identical forces to every part of the Earth, causing no precession." -TVF
I must be missing something. The precession effect (shift of the fixed stars) would be caused by the rotation of the entire solar system, not gravitational torquing of the Earth's equitorial bulge like lunisolar effects do. And of course nobody claims that such lunisolar effects do not occur. At that distance the torquing effect of a hypothetical binary companion could be ignored completely. The question is, are lunisolar effects alone enough to account for observations? And,
"Other planets have spin axis precession also, but at drastically different rates that depend on the amount of spin flattening and
distance from the Sun of those planets. The unseen companion is supposed to produce the same change for all planets because it is
rotating the whole solar system. But that is contradicted by observations." - TVF
I'd think we couldn't expect to see the effect on the other planets caused by the solar system's rotation from the vantage point of the Earth, since we are all on the same merry-go-round, so to speak. We should see only their local gravitational torquing from spin flattening, etc. We could in principle test the binary hypothesis by placing a camera on the surface of Mars and having it measure the position of the fixed stars at Mars' own vernal equinox for a few orbits. If all we see is Mars' measured local precession of -707" per century, the binary hypothesis is falsified. If extra shifting of the stars is seen, an additional effect is there which needs an explanation. (Don't ask me to ask for funding for this.)
I think I mentioned the seasons regressing through the calender, and you said the calender was set up to track the tropical year so that does not happen. What I intended to say was that today, the winter solstace in the northern hemisphere takes place when the earth is near perigee. Lunisolar precession or "wobbling" of the spin axis indicates that in 12,000 years the solstace will take place near apogee. The calendar will still say late December, and it will be winter, but the seasons in the northern hemisphere may be a little more extreme. On the other hand, if most of the precession effect is from solar rotation around a companion, the solstace will still be near perigee.
Finally, in your discussion of possible planetary explosion mechanisms elsewhere on the site, you state that stars need an ignition mechanism, which could be a fission chain reaction, but "...then dark stars of all masses might exist for which no ignition occurred." Would such a "dark star" be cold as well as dark?
Please Log in or Create an account to join the conversation.
- tvanflandern
- Offline
- Platinum Member
Less
More
- Thank you received: 0
18 years 2 months ago #9148
by tvanflandern
Replied by tvanflandern on topic Reply from Tom Van Flandern
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by nemesis</i>
<br />The precession effect (shift of the fixed stars) would be caused by the rotation of the entire solar system, ...<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Yes, a precession of the entire solar system can be imagined. But no such motion is observed. The axis of the Earth's orbit has no motion with respect to the fixed stars except the small one that is gravitationally forced on it by planetary perturbations. Precession is 5000"/cy, but there is less that 1"/cy of wiggle room to insert some other precession of unknown origin such as a dark companion. Moreover, the amount of that precession would be different for every planet. No known kind of force can rotate the whole solar system as if it were a rigid body.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">... not gravitational torquing of the Earth's equitorial bulge like lunisolar effects do.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">The entire observed precession is a motion of Earth's spin axis with respect to the fixed stars. Nothing else in the solar system -- including Earth's orbit, the Moon's orbit, any satellite, planet, asteroid, comet, or spacecraft -- shares this precession unique to Earth's spin axis.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">And of course nobody claims that such lunisolar effects do not occur. ... The question is, are lunisolar effects alone enough to account for observations?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Theory and observations now agree closely. At least 99% of the effect is a necessary motion of Earth's spin axis imposed by the gravity of Sun and Moon applying a torque to Earth's bulging equator. The small remainder is explained by Earth's slight "pear-shape" and other small deviations from an oblate spheroid. Again, next to nothing is left for a dark companion to do. And anything a dark companion did would change Earth's orbit, not its spin axis. So it would not be mistaken as a contributor to precession.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I'd think we couldn't expect to see the effect on the other planets caused by the solar system's rotation from the vantage point of the Earth, since we are all on the same merry-go-round, so to speak.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">That is incorrect. All terrestrial observations of things outside Earth's gravitational sphere of influence are referenced to the appropriate frame, which is often the Sun farme or the solar system barycenter frame. That is especially true of planetary radar ranging results and spacecraft results, which are almost blind to motions of Earth's spin axis, yet detect no unexpected rotations of the rest of the solar system.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">We could in principle test the binary hypothesis by placing a camera on the surface of Mars and having it measure the position of the fixed stars at Mars' own vernal equinox for a few orbits.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">We have such a camera in orbit around Mars, keeping a known posture with respect to the fixed stars and photographing the surface of Mars. If the surface had any unexpected motion, the camera pointing would soon need adjustment.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">If all we see is Mars' measured local precession of -707" per century, the binary hypothesis is falsified.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">So then your last hope would seem to be that an anomalous motion of the Mars spin axis exists, the spacecraft camera pointing had to be adjusted, and no one on the instrument team (including the geodesists trying to establish a precision mapping coordinate frame for Mars) has bothered to mention this as a major discovery of the project. Perhaps they already have enough funding and discoveries and don't need more?
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">today, the winter solstace in the northern hemisphere takes place when the earth is near perigee. Lunisolar precession or "wobbling" of the spin axis indicates that in 12,000 years the solstace will take place near apogee.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Naturally. Earth's north spin axis is pointed away from the Sun in January, when Earth is a perigee. Because of precession of the spin axis (only), in 12,000 years, the north spin axis will be pointed toward the Sun at perigee. Doesn't that prove that only Earth's spin axis changed during that 12,000 years? If the whole solar system had rotated and Earth's spin axis had not precessed, then the north spin axis would always point away from the Sun at perigee.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">if most of the precession effect is from solar rotation around a companion, the solstace will still be near perigee.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">We seem to agree about this geometry, but not about what it means for precession. We don't have to wait 12,000 years to see what will happen. We see these motions going on continually, and the perigee dates are moving through the seasons at a measured rate that will cause perigee to be in July in 12,000 years.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Finally, ... you state ... "dark stars of all masses might exist" ... Would such a "dark star" be cold as well as dark?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">I don't see how. Jupiter puts out more than twice as much heat as it takes in from the Sun. The other gas giants are also radiating significant internal heat. They would be all lit up in the infrared sky if they were as close as within the solar system. -|Tom|-
<br />The precession effect (shift of the fixed stars) would be caused by the rotation of the entire solar system, ...<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Yes, a precession of the entire solar system can be imagined. But no such motion is observed. The axis of the Earth's orbit has no motion with respect to the fixed stars except the small one that is gravitationally forced on it by planetary perturbations. Precession is 5000"/cy, but there is less that 1"/cy of wiggle room to insert some other precession of unknown origin such as a dark companion. Moreover, the amount of that precession would be different for every planet. No known kind of force can rotate the whole solar system as if it were a rigid body.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">... not gravitational torquing of the Earth's equitorial bulge like lunisolar effects do.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">The entire observed precession is a motion of Earth's spin axis with respect to the fixed stars. Nothing else in the solar system -- including Earth's orbit, the Moon's orbit, any satellite, planet, asteroid, comet, or spacecraft -- shares this precession unique to Earth's spin axis.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">And of course nobody claims that such lunisolar effects do not occur. ... The question is, are lunisolar effects alone enough to account for observations?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Theory and observations now agree closely. At least 99% of the effect is a necessary motion of Earth's spin axis imposed by the gravity of Sun and Moon applying a torque to Earth's bulging equator. The small remainder is explained by Earth's slight "pear-shape" and other small deviations from an oblate spheroid. Again, next to nothing is left for a dark companion to do. And anything a dark companion did would change Earth's orbit, not its spin axis. So it would not be mistaken as a contributor to precession.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I'd think we couldn't expect to see the effect on the other planets caused by the solar system's rotation from the vantage point of the Earth, since we are all on the same merry-go-round, so to speak.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">That is incorrect. All terrestrial observations of things outside Earth's gravitational sphere of influence are referenced to the appropriate frame, which is often the Sun farme or the solar system barycenter frame. That is especially true of planetary radar ranging results and spacecraft results, which are almost blind to motions of Earth's spin axis, yet detect no unexpected rotations of the rest of the solar system.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">We could in principle test the binary hypothesis by placing a camera on the surface of Mars and having it measure the position of the fixed stars at Mars' own vernal equinox for a few orbits.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">We have such a camera in orbit around Mars, keeping a known posture with respect to the fixed stars and photographing the surface of Mars. If the surface had any unexpected motion, the camera pointing would soon need adjustment.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">If all we see is Mars' measured local precession of -707" per century, the binary hypothesis is falsified.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">So then your last hope would seem to be that an anomalous motion of the Mars spin axis exists, the spacecraft camera pointing had to be adjusted, and no one on the instrument team (including the geodesists trying to establish a precision mapping coordinate frame for Mars) has bothered to mention this as a major discovery of the project. Perhaps they already have enough funding and discoveries and don't need more?
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">today, the winter solstace in the northern hemisphere takes place when the earth is near perigee. Lunisolar precession or "wobbling" of the spin axis indicates that in 12,000 years the solstace will take place near apogee.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Naturally. Earth's north spin axis is pointed away from the Sun in January, when Earth is a perigee. Because of precession of the spin axis (only), in 12,000 years, the north spin axis will be pointed toward the Sun at perigee. Doesn't that prove that only Earth's spin axis changed during that 12,000 years? If the whole solar system had rotated and Earth's spin axis had not precessed, then the north spin axis would always point away from the Sun at perigee.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">if most of the precession effect is from solar rotation around a companion, the solstace will still be near perigee.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">We seem to agree about this geometry, but not about what it means for precession. We don't have to wait 12,000 years to see what will happen. We see these motions going on continually, and the perigee dates are moving through the seasons at a measured rate that will cause perigee to be in July in 12,000 years.
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Finally, ... you state ... "dark stars of all masses might exist" ... Would such a "dark star" be cold as well as dark?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">I don't see how. Jupiter puts out more than twice as much heat as it takes in from the Sun. The other gas giants are also radiating significant internal heat. They would be all lit up in the infrared sky if they were as close as within the solar system. -|Tom|-
Please Log in or Create an account to join the conversation.
Time to create page: 0.454 seconds