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 Post subject: Planet found orbiting around FOUR suns PostPosted: 2012-10-16 04:14pm
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Wow!

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Richard A. Lovett in Reno, Nevada for National Geographic News
Published October 16, 2012

Step aside Tatooine. A newfound planet known as PH1 has double the suns of Star Wars' famous two-sun world, amateur astronomers have discovered.

Previously, six other planets had been found circling double stars, but "this is the first planet discovered in a four-star system," Yale planetary astronomer Megan Schwamb said Monday at a meeting of the American Astronomical Society's Division for Planetary Sciences in Reno, Nevada.

PH1, which is about 6.2 times Earth's width, orbits two of the stars, which are themselves orbited by a second pair.

One of the primary stars is superbright and 1.7 times larger than our sun. The other is dimmer and is only 41 percent the width of our sun. PH1 circles these two at about two-thirds the distance of Earth from our sun.

The other stars are far, far away—approximately 30 times the distance between Neptune and our sun. From that range, the stars would simply appear as a pair of brilliant pinpoints.

But don't expect that sunset scene in Star Wars: None of the four suns would be visible from the planet's surface.

That's because PH1 is a gas giant—about half as massive as Jupiter—and its surface would be shrouded with thick clouds, which would make seeing stars difficult.

Even if there were a cloudless atmosphere, Schwamb added, the light from a nearby superbright star would likely make stargazing impossible on PH1.

(Related: "'Tatooine' Planet With Two Suns Could Host Habitable Moon?")

Odd Planet a Milestone

The odd planetary system is a milestone for a few reasons. For one, it challenges conventional notions of how planets form, Schwamb said.

"The discovery of these systems is forcing us to go back to the drawing board to understand how such planets can assemble and evolve in these dynamically challenging environments," she said in a statement.

What's more, PH1 is also the first planet found by participants in the Planet Hunters project, a collaboration of Yale University and the Zooniverse, a website that supports citizen science.

As part of that program, amateur scientists scan data from NASA's Kepler Space Telescope, looking for the tiny variations in starlight that occur when planets pass between us and their host stars.

Such planets can be tricky to spot in multiple star systems, Schwamb said, because the stars themselves are passing in front or behind each other, causing additional fluctuations in the light seen from Earth.

"The traditional method would have made this hard to do," said Schwamb. "With citizen science, you get a lot of pairs of eyes to stare at this."


All that we need now is a planet with SEVEN suns just like in Isaac Asimov's Nightfall. :mrgreen:

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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-16 04:24pm
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Boeing 757 wrote:
All that we need now is a planet with SEVEN suns just like in Isaac Asimov's Nightfall. :mrgreen:

I could have sworn that planet had 6 suns. Wikipedia backs me up.

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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-16 05:51pm
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Why would this challenge our understanding of how planets form?



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-16 05:54pm
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Feil wrote:
Why would this challenge our understanding of how planets form?


It's not s much this particular planet but the exoplanets found so far. We used to have a model based on our solar system with small rocky planets forming close in and large gaseous planets formign further out where the volatile gasses wouldn't evaporate from the sun's radiation.

Now though we find planets bigger than Jupiter orbiting sun-type stars at closer than Mercury's orbit. Clearly our model was wrong and our solar system is distinctly atypical.

EDIT: Oops, also, we used to be fairly certain that there weren't stable orbits around multi-star systems. So finding a planets thats formed around one pair of a binary-binary system is a big "WTF?" moment.



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-16 06:05pm
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Dave wrote:
Boeing 757 wrote:
All that we need now is a planet with SEVEN suns just like in Isaac Asimov's Nightfall. :mrgreen:

I could have sworn that planet had 6 suns. Wikipedia backs me up.


You're right, there were only six! How dare I not be up to date on my Asimovian knowledge. I guess I should head over to my local library and rectify that. :lol:

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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-16 06:39pm
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Here is another short piece with a video about its orbit, on CNN. Miss Congeniality seems to be soooo intrigued by this new find. :lol:

Seriously though, I wonder how far apart each of these stars are from one another. How does the gravity of four stars not knock it out of its orbit?

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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-16 06:45pm
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It says in the article, the two pairs of stars orbit each other at 30 times Naptune's orbit around the Sun. Neptune has an average distance of 30 AU so these pairs of stars orbit each other at 900 AUs distance. Far enough that even bright stars appear as bright pinpricks rather than distinct suns.



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-16 07:11pm
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Mind boggling. And two of the four are even closer than the Earth to our Sun.

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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-16 08:00pm
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Boeing 757 wrote:
Dave wrote:
Boeing 757 wrote:
All that we need now is a planet with SEVEN suns just like in Isaac Asimov's Nightfall. :mrgreen:

I could have sworn that planet had 6 suns. Wikipedia backs me up.


You're right, there were only six! How dare I not be up to date on my Asimovian knowledge. I guess I should head over to my local library and rectify that. :lol:

Escape Pod has a fairly good narration of Nightfall available for free if you have to get your hands on it faster. (90 minute MP3)

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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-18 03:06pm
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Eternal_Freedom wrote:
Feil wrote:
Why would this challenge our understanding of how planets form?


It's not s much this particular planet but the exoplanets found so far. We used to have a model based on our solar system with small rocky planets forming close in and large gaseous planets formign further out where the volatile gasses wouldn't evaporate from the sun's radiation.

Now though we find planets bigger than Jupiter orbiting sun-type stars at closer than Mercury's orbit. Clearly our model was wrong and our solar system is distinctly atypical.


Okay, this part makes sense. Thanks.

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EDIT: Oops, also, we used to be fairly certain that there weren't stable orbits around multi-star systems. So finding a planets thats formed around one pair of a binary-binary system is a big "WTF?" moment.


I'm confused as to why we would think that multi-star systems with planets couldn't be stable. Rare, yes - multiple star systems are relatively rare, planets are relatively rare, and the multiple stars would create tidal changes that would restrict the amount of available stable orbits. But we see multi-body systems that get along just fine - our own being a prime example. Is there some critical point in the math at which increasing the mass of the various bodies orbiting one another leads to unstable orbits? Do you know of anywhere I could look at the equations or modeling of this sort of thing? It seems like an interesting question, and I get to feel smug about my ignorance of the impossibility of stable orbits around multi-star systems being proven right :P



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-18 04:25pm
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Rare, yes - multiple star systems are relatively rare, planets are relatively rare, and the multiple stars would create tidal changes that would restrict the amount of available stable orbits.


Meh, not really true. Most stars in the galaxy are actually binary...single stars such as our own are the minority. Also it's becoming obvious that planets are actually so common, that it's possible every star has them.



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-18 06:21pm
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Feil wrote:
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EDIT: Oops, also, we used to be fairly certain that there weren't stable orbits around multi-star systems. So finding a planets thats formed around one pair of a binary-binary system is a big "WTF?" moment.


I'm confused as to why we would think that multi-star systems with planets couldn't be stable. Rare, yes - multiple star systems are relatively rare, planets are relatively rare, and the multiple stars would create tidal changes that would restrict the amount of available stable orbits. But we see multi-body systems that get along just fine - our own being a prime example. Is there some critical point in the math at which increasing the mass of the various bodies orbiting one another leads to unstable orbits? Do you know of anywhere I could look at the equations or modeling of this sort of thing? It seems like an interesting question, and I get to feel smug about my ignorance of the impossibility of stable orbits around multi-star systems being proven right :P


The critical point is that in single-star systems all the planets are orbiting the Sun. Yes, each body has an effect on the others but when compared to the effects of the sun it's trivial. For instance, in EArth's case we have a one solar mas star pulling on us at 1 AU, we also have a less-than-one-hundredth solar mass planet pulling on us from a greater distance. The effect is too small to compare.

However, add another star to the mix and it get's wonky. Suddenly, you can have (at some points in the orbit) another object of comparable mass to your primary star pulling on you from the opposite direction to your primary. THat's goign to mess up orbits, unless they are in some special cases.

Mostly, stable planetary orbits in multi-star systems seem to be the planet orbiting one star while the companion orbits the star a lot further out. Or the planet orbits a pair of stars far enough out that the gravitational pul is effectively combined. Or, in this case, the planet orbits a pair of stars, while a second pair of stars orbit the first pair (the pairs actually orbit each other) at a great distance. 900 AU in this case.

And yes, about two thirds of all star systems are believed/expected to be binaries. Combine us being in a single-star system with our distinctly atypical formation of planets and we live in one weird solar system.



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 09:03am
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I would remind people "The other stars are far, far away—approximately 30 times the distance between Neptune and our sun. From that range, the stars would simply appear as a pair of brilliant pinpoints"

So they're massively far away, and thus orbiting incredibly slowly too. Teeny tiny effects.



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 10:40am
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Eternal_Freedom wrote:
Combine us being in a single-star system with our distinctly atypical formation of planets and we live in one weird solar system.

Atypical how? Hot Jupiters are just easy to find, thus confirmation bias. First planetary system ever found is pretty much identical to Mercury-Mars range of our own, after all.

madd0ct0r wrote:
So they're massively far away, and thus orbiting incredibly slowly too. Teeny tiny effects.

Yes, but it orbits its main two stars that are close enough to cause problems.

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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 10:54am
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Jupiter-sized planets are easy to find, so yeah you're right we've found a lot of them. But what is surprising is that a huge number of these large planets are as close to their star as Mercury is to our own (even closer too). We find it so often in fact, that it appears to be the norm to have a hot Jupiter. In our own solar system, we have the dual weirdness of having only a single star AND having *all* our gas giants orbiting far away.



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 11:07am
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Planets that orbit close to their stars also have a greater observable effect. It's not just Jupiters that are the easiest planets to find; Hot Jupiters are easier still and thus going to show up disproportionately for at least some time.



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 11:29am
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Grandmaster Jogurt wrote:
Planets that orbit close to their stars also have a greater observable effect. It's not just Jupiters that are the easiest planets to find; Hot Jupiters are easier still and thus going to show up disproportionately for at least some time.



Exactly. I'm expecting most solar systems to have a somewhat "Sol-like" distribution of small rocky planets and large gas giants...it makes sense from an orbital mechanics standpoint, but I'm really curious why we never developed a hot Jupiter like everybody else seemed to.

One theory...in our own solar system, the outer planets were initially much closer to the sun than they are now. An orbital resonance between Jupiter and Saturn spread out the gas giants and even flipped the orbits of Uranus and Neptune (Uranus used to be outside of Neptune, and the resonance slingshotted Neptune way past Uranus). I wonder if a similar mechanism could have caused planets to migrate in closer to the star, or if it's more likely that they actually formed there (strange as it may seem).



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 12:51pm
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Borgholio wrote:
Exactly. I'm expecting most solar systems to have a somewhat "Sol-like" distribution of small rocky planets and large gas giants...it makes sense from an orbital mechanics standpoint, but I'm really curious why we never developed a hot Jupiter like everybody else seemed to.


It could have fallen into the Sun very early on in the formation of the solar system, or been ejected. We know it's possible to have gas giants drifting into very close orbits without ejecting the terrestrial planets in the system, from star systems like Kepler-20.



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 12:55pm
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That could be. I think once we map more and more planets we'll actually be able to develop a model that could explain it. Now that the Centauri system is strongly suspected to have planets, I think that'll be one of our first targets to examine with the next generation of telescopes. It's close enough that we might see some fairly good detail and study that system over a long period of time.



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 02:04pm
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Borgholio wrote:
Exactly. I'm expecting most solar systems to have a somewhat "Sol-like" distribution of small rocky planets and large gas giants...it makes sense from an orbital mechanics standpoint, but I'm really curious why we never developed a hot Jupiter like everybody else seemed to.

..."everybody else sees to" ONLY due to confirmation bias. Even if Hot Jupiter planets were rare, absolute minority in fact, they would still be found most often. If you need, imagine field with ten thousand rabbits and ten elephants - if you watch from distance with bad binoculars, all you see are elephants despite them being less than 1% of field's population.

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One theory...in our own solar system, the outer planets were initially much closer to the sun than they are now. An orbital resonance between Jupiter and Saturn spread out the gas giants and even flipped the orbits of Uranus and Neptune (Uranus used to be outside of Neptune, and the resonance slingshotted Neptune way past Uranus). I wonder if a similar mechanism could have caused planets to migrate in closer to the star, or if it's more likely that they actually formed there (strange as it may seem).

Do you know how much energy you need to move something the mass of Jupiter out of Sun's gravity well? Migration only happens inward, unless the gravity is already too weak to strongly hold the other body which is not the case and certainly wouldn't be around Earth's orbit.

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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 02:22pm
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Irbis wrote:
..."everybody else sees to" ONLY due to confirmation bias. Even if Hot Jupiter planets were rare, absolute minority in fact, they would still be found most often. If you need, imagine field with ten thousand rabbits and ten elephants - if you watch from distance with bad binoculars, all you see are elephants despite them being less than 1% of field's population.


I'm not talking about the ratio of hot Jupiters to other planets, I'm talking about the ratio of hot Jupiters to stars. So far, the ratio is very high. It appears many (if not most) stars have at least one of them.

Irbis wrote:
Do you know how much energy you need to move something the mass of Jupiter out of Sun's gravity well? Migration only happens inward, unless the gravity is already too weak to strongly hold the other body which is not the case and certainly wouldn't be around Earth's orbit.


Yes it's a staggering amount of energy, but I'm sorry to say you are incorrect. Migration frequently happens outwards as a result of various forces including orbital resonance. Our own solar system is proof enough of that. We had not one, not two, but THREE planets migrate outwards in the distant past. Saturn, Uranus and Neptune used to be much closer to the sun than they are now. Jupiter pushed Saturn out until they had a resonance going. That resonance actually flung Neptune PAST the orbit of Uranus to where it is now, and nudged Uranus further out in the process.



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 04:18pm
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Borgholio wrote:
I'm not talking about the ratio of hot Jupiters to other planets, I'm talking about the ratio of hot Jupiters to stars. So far, the ratio is very high. It appears many (if not most) stars have at least one of them.

What, 500-600 found to tens of thousands of stars in our neighbourhood alone is high ratio? :|

On the contrary, our vicinity shows they are rare, with none in at least 10 closest stars. Had they been so common, we would have found them a lot faster.

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Yes it's a staggering amount of energy, but I'm sorry to say you are incorrect. Migration frequently happens outwards as a result of various forces including orbital resonance. Our own solar system is proof enough of that. We had not one, not two, but THREE planets migrate outwards in the distant past. Saturn, Uranus and Neptune used to be much closer to the sun than they are now. Jupiter pushed Saturn out until they had a resonance going. That resonance actually flung Neptune PAST the orbit of Uranus to where it is now, and nudged Uranus further out in the process.

Except, in all three cases, Jupiter, heaviest planet provided the energy needed to push the other three giants away. Energy doesn't come from nowhere, each time Jupiter paid for it in momentum and/or orbit. For your scenario to become true, there would need to be even more massive planet that Jupiter between the other 4 giants and sun to push them away - something so massive it would blur size between planet and star, something that would have utterly obliterated any planets or protoplanetary discs, orbiting somewhere around Earth's orbit. Do you see the problem now?

And where it went? The only solution is ramming Sun, and collision of 2 such big objects would literally sterilize whole solar system with gigantic radiation burst and surely left some signs.

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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 05:02pm
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Irbis wrote:
What, 500-600 found to tens of thousands of stars in our neighbourhood alone is high ratio? :|

On the contrary, our vicinity shows they are rare, with none in at least 10 closest stars. Had they been so common, we would have found them a lot faster.


It is when you consider the limitations of our means of finding them. Even Kepler can only spot planets if they make a transit in front of their stars in star systems that are "edge-on" in terms of visibility. That closes off most star systems, and the rest are heavily biased towards having super-close-in planets where confirming the transits is easiest.

Just look at the Alpha Centauri planet. It was lucky that we even found it, since usually the two stars are so bright that they swamp out any light reflected off of the planet they found.



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-19 05:30pm
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Irbis wrote:
What, 500-600 found to tens of thousands of stars in our neighbourhood alone is high ratio? :|


Yes it is, especially considering that the actual number of planet candidates detected by Kepler is "only" in the 2000-ish range. 1 out of 4 planets being a hot (or not hot but inner-orbit) gas giant? That's a really high ratio actually...considering in our own solar system the ratio is 0 to 8.

Irbis wrote:
On the contrary, our vicinity shows they are rare, with none in at least 10 closest stars. Had they been so common, we would have found them a lot faster.


That point is irrelevant, because most of the hot Jupiters were detected by Kepler, and Kepler is not looking at the 10 closest stars.


Irbis wrote:
Except, in all three cases, Jupiter, heaviest planet provided the energy needed to push the other three giants away. Energy doesn't come from nowhere, each time Jupiter paid for it in momentum and/or orbit. For your scenario to become true, there would need to be even more massive planet that Jupiter between the other 4 giants and sun to push them away - something so massive it would blur size between planet and star, something that would have utterly obliterated any planets or protoplanetary discs, orbiting somewhere around Earth's orbit. Do you see the problem now?



Orbital resonances can do a tremendous amount of work. Please read - http://en.wikipedia.org/wiki/Nice_model

It is a widely accepted theory that the gas giants could not have formed so far away from the sun as quickly as they did. They must have formed closer to the sun and migrated outwards. I see no problem at all with the idea that two large planets working in rhythm can move two smaller planets to a larger orbit.


Irbis wrote:
And where it went? The only solution is ramming Sun, and collision of 2 such big objects would literally sterilize whole solar system with gigantic radiation burst and surely left some signs.


Right so which idea makes more sense? Two planets in an orbital resonance causing the solar system to destabilize, or a mystery star that blew through the solar system and left no trace of it's existence?



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 Post subject: Re: Planet found orbiting around FOUR suns PostPosted: 2012-10-20 09:41am
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Guardsman Bass wrote:
It is when you consider the limitations of our means of finding them. Even Kepler can only spot planets if they make a transit in front of their stars in star systems that are "edge-on" in terms of visibility. That closes off most star systems, and the rest are heavily biased towards having super-close-in planets where confirming the transits is easiest.

Just look at the Alpha Centauri planet. It was lucky that we even found it, since usually the two stars are so bright that they swamp out any light reflected off of the planet they found.

But you just repeated my point - yes, small planets are hard to spot. That doesn't change the fact that big planets are easy to spot, and we never saw any Hot Jupiters in closest systems, yes, we saw a lot of them but scattered all over so they can't be called common.

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Yes it is, especially considering that the actual number of planet candidates detected by Kepler is "only" in the 2000-ish range. 1 out of 4 planets being a hot (or not hot but inner-orbit) gas giant? That's a really high ratio actually...considering in our own solar system the ratio is 0 to 8.

1 out of 4 planets being hot giant when they are hundreds to thousands of times easier to spot shows the ratio is low, actually, and will only drop as our detection methods will improve.

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Orbital resonances can do a tremendous amount of work.

Again, work doesn't come from nowhere. Do read it, Jupiter moved the other 3, being much more massive. You want to move Jupiter? Congratulations, you need something far more massive to impart energy to destabilize it away from Sun's gravity well. The link you posted replaces my work assumption of single massive planet with millions of planetesimals, precisely to explain point you failed to address: that something must pay for moving Jupiter away from Sun, orbital resonance isn't magical free energy generator.

Think about it for a second, you think the resonance stopped? Nope. Then why the giant planets don't move? Because there is no more easy energy to be tapped to move them, unlike what you posted. That's why also all the hot Jupiters stayed in place - no magical energy to be tapped, planet can't move.

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