Solar Systems Like Ours Are Likely To Be Rare

KentuckyFC writes "Astronomers have discovered some 250 planetary systems beyond our own, many of them with curious properties. In particular, our theories of planet formation are challenged by 'hot Jupiters,' gas giants that orbit close to their parent stars. Current thinking is that gas giants can only form far away from stars because gas and dust simply gets blown away from the inner regions. Now astronomers have used computer simulations of the way planetary systems form to understand what is going on (abstract). It looks as if gas giants often form a long way from stars and then migrate inwards. That has implications for us: a migrating gas giant sweeps away all in its path, including rocky planets in the habitable zone. And that means that solar systems like ours are likely to be rare."

Well, that does it...

Get Bruce Willis on the phone, time to go "Armageddon" on Jupiter's ass.

Re:Well, that does it...

On the other hand, the rest of us wish you'd learn to spell "probability".

Re:Well, that does it...

On the other hand, the rest of us wish you'd learn to spell "probability".

Maybe he should use a spell chequer!!

Re:Well, that does it...

Whatever... this is naval gazing and conjecture, no more credible than Intelligent Design. These guys have a few data points, they create a highly convoluted system that seems to account for their data points, then the moment they get more data, they start over. Again and again.

A good critical thinker should know when to say "We don't have a fucking clue" if they want to be taken seriously. But then, it's all about money, isn't it?

Re:Well, that does it...

Whatever... this is naval gazing and conjecture, no more credible than Intelligent Design. These guys have a few data points, they create a highly convoluted system that seems to account for their data points, then the moment they get more data, they start over. Again and again.

Data points which are skewed by the fact that planets with a large mass (relative to the star) orbiting close to the star are easier to detect by techniques based on star wobble and transit light level and so are going to be massively over represented in the list of known planetary systems.

Re:Well, that does it...

I'm no expert, but as I recall the major problem with probes into the gas giants is that the immense pressure inside of them would crush anything we're capable of making, and electromagnetic interference from the constant storms would make it impossible to transmit any data out.

Plus, every time anyone mentions sending probes into Uranus over at NASA, nobody can stop giggling long enough to seriously work on the problem.

Re:Well, that does it...

Haha. I don't know about sending Bruce WIllis, but this does make me wonder why we have never (to my knowledge...) sent a probe INTO one of the gas giants.

Your geek credits have been officially revoked.

Galileo had a probe that was dropped into the atmosphere of Jupiter and it transmitted data for 58 minutes [nasa.gov] before it stopped. Hell, we even crashed the Galileo spacecraft into Jupiter to prevent contaminating Europa or Callisto with organisms from Earth.

Re:Well, that does it...

We have.

in 1995 by the Galileo a probe was dropped into Jupiter.

http://apod.nasa.gov/apod/ap951207.html [nasa.gov]

But if you think it will just sink in until it 'hits' then check your physics on large gas giants again.

Rare?

I didn't RTFA, but I will when I get home.

But on the surface it seems more to me that they're just saying that solar systems have a life cycle that is marked by the location of gas giants. I don't really think that means that our setup is rare.

But if I am misinterpreting the blurb and that is what they're proposing I would still say we need to hold our horses on any real judgement. We've found these solar systems because our current method of seeking these solar systems out is going to be more likely to find this kind of activity as opposed to what we have here at home. I think we're jumping the gun a bit on this one. I say let them work it out for a couple of more decades and even then we should be a bit more cautious about such sweeping statements.

Re:Rare?

I agree. In addition, 250 systems really isn't a lot. I'm just a lay-person but it occurs to me that the easiest ones to examine via red-shift are those with a gas giant close to the sun.

Re:Rare?

The method used to find these systems are changes in the star's brightness when the planet passes in front of the star - so systems with large planets in close orbit are the ones to be noticed first. If you have a planet like Jupiter with an orbital period of around 12 years, you're much less likely to catch that event compared to those "unexpected" systems with short periods.

Re:Rare?

The parent is correct that there is a selection bias in our detection methods of planets that favours systems with gas giants close to the sun. However, this has nothing to do with the conclusions of the article. What they are saying is that, initially, the discovery of so many closely orbiting gas giants was confusing given that their models of planet formation show gas giants developing far away from the sun. What they have found through simulations is that gas giants naturally migrate inwards as the solar system evolves. So a 4 billion year old system like ours with gas giants far from the sun in unlikely. This conclusion comes from the simulations of solar system evolution, not from the observational data.

Re:Rare?

They're not actually determining that solar systems like ours are rare from the observations. The observations were incompatible with our current thinking on solar system formation. Solar system formation was reexamined, and a more-accuracy theory of solar system formation suggests that systems like ours are unlikely.

Re:Rare?

Extensive computer simulation from basic principles. Not, "well, this theory more closely matches what we've recently observed, so it's more accurate".

Believe it or not, logical weaknesses that can be caught by the Slashdot crowd are almost always noticed by scientists. It's just that Slashdot doesn't read the articles.

Re:Rare?

But that doesn't make them not rare. If there's 100 billion star systems, and even just 1 million stars in each, you are looking at 100,000,000,000,000 star systems. Even if there is a .000001% chance of a star system like ours existing, it means that there are 1,000,000 star systems that are like ours. So they could be both very rare, and yet still very likely to happen.

Re:Rare?

That's still rare. If we assume that there's 100 billion galaxies in the world (which Wiki says is the current estimate), and put a star system like ours on the rare end of the scale as in 1 per galaxy, you do end up with 100 billion star systems like ours. But that's still extremely rare, as it's pretty much impossible to find one.

Look at it another way: In 2006 the world supply of platinium was about 217,000 kg. That's about 1,112,341 mole or 667,404,810,235,590,822,414,959,709,663 molecules. That's a BIG number, but it's still a very rare metal. So rare in fact, that 2006 world supply wouldn't even let you give 1 gram of platinum to each resident of the United States.

Big numbers doesn't indicate how rare something is. Rare is an indication of the chance/risk of encountering something. And in a huge universe with 100 billion galaxies, 100 billion star systems like ours is RARE! In fact it's so rare, that it might as well not exist anywhere else, because without visiting other galaxies, we'd never know they were there.

This appears to be a "When you are a hammer ..."

"... Everything looks like a nail" situation to me. We've only really had the ability to discover LARGE planets around solar systems. Also, the shorter the orbit period, the easier it is to detect.

So logically, the planets we've found to date look NOTHING like those of our solar system. Jupiter's orbital period is 4332.71 days!!! And we are comparing that to the VAST majority of discovered planets(hot Jupiters) with orbital periods of less than 10 days?

Seems like this article belongs in the "Are US Voters Informed Enough About Science?" thread if you ask me.

Re:This appears to be a "When you are a hammer ...

Yes, our theories were WAY off. No one predicted that these hot Jupiters were out there. Now they make up almost all of the planets we've detected to date. The point I was trying to make is that we can't detect solar systems like ours yet. Unless MAYBE it was in the alpha centaurus system and then MAYBE if it's Jupiter equivalent were to pass in front of one of the stars.

Please, tell me how many exosolar planets we've found with orbital periods greater than 365 days? How about 4000+ days like Jupiter?

Talking about how rare we are, without even another example, because we lack the ability, is just another theory that will fall - kinda like the planet formation theories that lacked the ability to predict "hot Jupiters". Now they have gone to the other extreme and theorized that EVERY solar system starts out with hot Jupiters. You know, because that is all we can presently detect.

How is that irrelevant? It's EXACTLY the "To a hammer, all looks like a nail" analogy I started with. Since that is all we have the ability to find at present, now all solar systems must start out that way?!?!?!?

This is the same mistake all the theorists made to start with, since all we had was our own solar system to base this upon. Now they have gone exactly the opposite way in their theories which is repeating the same mistake they initially made.

Yes, you adapt your theories based upon more and more observational data. But when you KNOW your observational data is limited to one subset of possible outcomes(which makes our own solar system damn near impossible to form) and you claim "victory", that's just very illogical to me.

Hmmm

Even if solar systems configured like ours are rare, it doesn't suggest that is a problem for either the development of life or intelligence as we'd recognize it (and really is no problem for any other forms of "life").

A gas giant in the "habitable" zone may have multiple moons that end up habitable. If Jupiter was in Earth's orbit its entirely possible 2-3 or more of its moons would be habitable in some form.

That both increases the odds by having more places habitable, but increases the possibility of panspermia, so you could actually have greater diversity in that situation.

The planets may seek warmer climes in winter..

Are you suggesting that Jupiters migrate?

--
Incoming!

It's not all hot Jupiters out there

The data set seems a little biased.

The interesting data is not how many hot Jupiters are found, but how many stars do not have hot Jupiters.

Here's a list of extrasolar planets [exoplanets.org] (last updated in January); and another list [exoplanet.eu]. Note the large number of stars that have planets found with mass less than Mj. The converse of that is that those stars do not have planets of mass greater than Mj. The problem, of course, is that negative results are much less published than positive results. However, here is a list of three published papers that listed stars with no planets found [exoplanet.eu] (that is, no planets large enough to detect-- which is to say, no hot Jupiters. This list is somewhat out of date, as of 2006.)

So the story is a little incomplete. Some solar systems have hot Jupiters, which in their migration inward disrupt smaller, earthlink planets... but by no means all.

Re:first post

Nothing says "sanity" like a preemptive defense.

Re:first post

Outsider theories always have the burden of proof on their own shoulders. To paraphrase someone famous, "there are many questions fools can ask that wise men struggle to answer." There's no where this applies more than in science. Creation Science can throw out some sticky questions and make some points that are hard to disprove.

But Science is about proving things, not suggesting every possible idea and disproving them one by one. For a well established idea that has made a lot of successful predictions, even a known incomplete idea like the standard cosmological model, to be tossed aside, there needs to be an overwhelming amount of evidence, not just some compelling questions.

If an alternative model of the universe explains the preponderance of evidence we already have (such as the background radiation, the count of galaxies, the scarcity of structures above a certain scale, the calculated mass of galaxies, the total amount of gamma radiation etc.) as well as a current theory, as well as making successful new predictions that existing models failed to make, then over a process of several years, people in the field would become convinced, and as the literature is peer reviewed, the dogma would shift. But established scientific ideas are SUPPOSED to be dogma. It isn't politics. Equal time isn't given to competing ideas, that's not the way it works. There are too many bad scientists and professional crackpots, the system would collapse without a hierarchy of opinion.

And all science works this way and always has. Even the sciences that cure disease and deliver technological miracles. Since those things keep happening, I'm confident as a semi lay person that science, while certainly getting many small details wrong and making mistakes and sometimes taking too long to come to the right conclusions, is still heading in a monotonically positive direction.

Re:first post

But Science is about proving things, not suggesting every possible idea and disproving them one by one.

Where on Earth did you get that idea? One of the first things you learn about science is that it doesn't prove anything, only disprove. The scientific method is a three step process:

1. Observe.
2. Hypothesise (and predict).
3. Test.

You observe phenomenon, create a theory that explains it and makes some predictions and then test these predictions. If the observations don't match the predictions you either discard or refine the theory. If they do, then you keep it around until you find some new observations that don't match up with the predictions.

The reason creationism is not science is that it makes no testable predictions. Whether it is true or not can not be tested and so is an irrelevant question to science.

Re:wake me up

That's Gliese 581c, which is merely five times the mass of the Earth --- and they only detected it because it orbits at one fourteenth of Earth's orbit. In other words, it's a heavy planet very, very close to its sun. The only reason it was described as 'Earth-like' is that Gliese 581 itself is a red dwarf, which means it's much cooler than Sol, which puts 581c in the star's life zone.

So, while it's theoretically possible that 581c could support life, it's still not really Earth-like. We're still a long way off from being able to detect Earth-sized planets at Earth-orbit distances from Sol-like stars.