Saturday, July 10, 2010

Planets Gone Wild, Life as We Know It, and Orbital Mechanics

"Renegade Planets: Weird Alien Worlds Challenge Theories" (July 8, 2010)

"Over the past 200 years, a standard model has emerged to explain how solar systems form. Using our own solar system as a guide, the model explains the existence of a central star (our Sun), an inner system of rocky, 'terrestrial' planets, and an outer system of 'gas giant' planets, all orbiting in nearly the same plane of rotation as the central star.

"Recent discoveries of planetary systems around other stars have challenged this model. These exoplanet discoveries have included gas giant planets in close orbit around their stars, some of which are in radically different planes of rotation from their primary stars..."

And an unexpectedly large portion of those big planets aren't just out of their star's plane of rotation - they're in retrograde orbits. They're going around 'backwards.'

That's not what the nice, orderly, "standard" model predicted. Not even close.

As I've written before, it's nice when observations confirm existing theories and models. It's exciting when they don't - because that shows that we've got more to learn. Sometimes, a lot more to learn.

The article tells about a new model that explains some - but not all - of the newly-discovered strange planets. My guess is that there will be more explanations coming in the next few years.

One thing about what we're discovering about planetary systems is that they're not all - or even most - like the nice, neat, orderly system we live in. Part of that may be because the detection techniques we've got so far pick up big, heavy planets orbiting close to their some cases, that's the only sort of planet the technique can detect.

If the sort of planetary system we're in is actually rare, planets harboring life are probably rare, too. It's taken a long, long time for life to develop on Earth, and we probably wouldn't be here if something the size of Jupiter had been ky-yiying around the inner Solar system, pulling nearby planets into new orbits.

I've watched the conventional wisdom about whether planets circle other stars swing change from the assumption that there might be a tiny handful of planetary systems in the universe to thinking that other Earths are common as dirt.

Actually, since we're not up to our armpits in a Galactic Empire's equivalent of oil drums and six-pack rings, selling tacky souvenirs to space-alien tourists: my guess is that there aren't all that many places like Earth out there. At least, not with people like us.

But that might have more to do with what we're like - not how the Solar system is arranged.
Which I've discussed in another blog.

Vaguely-related posts:
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