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."

Comments

giants

[Anonymous Coward]

I thought it was commonly understood that for a solar system like ours to exist, that there needs to be a gas giant to act as a "protector" for the habitable planet(s). That is, the larger planet acts as a gravity well to lure some of the larger objects that could collide into the habitable planet. From the summary, it merely seems to be saying that the gas giant forms closer to the star than originally thought, but that it migrates outwards later in its life and helps to clear a zone for the habitable planet to exist.

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

[SengirV]

"... 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.

Hmmm

[tgd]

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.

Re:Well, that does it...

[eln]

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:Rare?

[Hektor_Troy]

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.

Calculating a planetary system.

[Z00L00K]

Personally I think it's hard to decide if our planetary system is rare or not just by computer simulations. There are too many factors involved to make it easy to calculate how a planetary system evolves.

There have been many guesses over the last century about how the planets did form. But from the data we now have from a few other planetary systems we can at least say that a few of them have large planets (gas or not remains to be seen).

And what would say that a planet has to be the size of earth to provide for life? A gas giant may be good for life too, but maybe not the life we know here.