http://www.livescience.com/space/080721-mm-solar-systems.html

The study concludes that may be just "6 to 10 percent" of all star systems have Jupiter-size or larger gas giants.

I think this number as it applies to solar systems specifically like ours, is likely even lower. Unlike every extrasolar planetary system we've discovered, our gas giants orbit a good distance from the Sun, with terrestrial planets orbiting closely. That's the opposite of the star systems we've detected so far in which large gas giants orbit very closely to their stars.

Now, there *is* a bias in our detection method; it's MUCH easier to detect star systems in which a gas giant is orbiting very closely to its star (because of the wobble method of detection)...hence, one reason why they make up most of the systems we've so far detected.

BUT, current theory regarding the formation of our solar system seems a bit complex, with factors like outward migration of Neptune influencing the final positions of the planets.


Just my two cents, but I have a hunch that "hot jupiter" star systems are probably more common than systems like ours, where gas giants lie further from their star. And it seems that systems which can even form a gas giant in the first place make up only 6-10 percent of stars!....

With all the "Jupiters" we've seen around nearby stars there should be a lot of "Earths" we can't see, too, since Earths are 300 times lighter.

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With all the "Jupiters" we've seen around nearby stars there should be a lot of "Earths" we can't see, too, since Earths are 300 times lighter.

In the "hot Jupiter" systems we've detected so far, any Earth-sized terrestrial planets within them would lie outside of the habitable zone, since that zone would be dominated by the super gas giants we've seen so far.

This leads some to speculate that any moons orbiting those gas giants may themselves be habitable (analogous to Europa, perhaps). Perhaps there could be Earth-like worlds with stable surface oceans orbiting those gas giants as well?