Wednesday, January 25, 2006



Almost ten years ago, scientists discovered the first extrasolar planet. I ran around the office in whic I worked (a property management company in San Francisco), waving the paper in my hands, going from room to room and telling everyone the big news. My coworkers, sadly, weren't impressed, and more than a few of them were surprised that we hadn't already discovered any planets outside our own solar system. I doubt anything other than aliens arriving on the White House lawn would have come as any kind of surprise to them, and even then they'd have been comparing the real extraterrestrials with all of the aliens they'd seen in movies, and would have been disappointed if the reality had been any less dramatic than fiction.

In the decade since then, astronomers just keep discovering new planets all the time, and the majority of the populace cares even less than they did about the first. And even if they've all been massive monsters in tight, if sometimes eccentric, orbits around their suns, with no hope for life as we know it, it's still continuing evidence that planets are as common as dirt. But most Americans, raised on science fiction and stories of alien abduction, have never realized there was any question about that, one way or the other. So I doubt that there will be celebratiosn in the streets in response to the news that scientists have been successful in identifying a nearly Earth-like planet using gravitational microlensing, but I think it's pretty damned keen.

Come on, Chris, you can't be discounting the multiple discoveries of Jupiter-like worlds orbiting within the parent star's "habitable zone" now, are you? I count that almost on par as this new discovery, since evidence from our own solar system (admittedly a small--but consistent--sample) indicates massive moons may well be very common. Put Jupiter in Earth's orbit, and not only Europa, but Ganymede and Callisto suddenly become potential havens for life.

But yeah, the new discovery is groovy/cool.
Jayme, I stand corrected. I was indeed completing overlooking the fact that these supermassive monsters could have Earth-like moons. Even better!
I think it's pretty damn keen too, although this rocky world is still five Earth sizes. But still, no reason that should rule out life. What your guy in the street needs, I think, is a picture and a name. A couple of years back, under Goldin, NASA were developing a spaceborne telescope specifically to grab full disc shots of extrasolar planets, because as Goldin says, when we see new land we want to go there. I wonder if recent setbacks have put paid to that?
There's some bitter irony, I think, to the fact that Bush started pushing his agenda for manned space missions (which I'm all for, though I disagree entirely with their plans To Boldly Go Where We've Gone Before, and the Kitchen Sink Included mission plans; I'm much more an advocate of something like Robert Zubrin's Mars Direct program), something like a matter of months after all funding was cut for the Breakthrough Physics Propulsion program at NASA. BPP was the only concentrated effort I'm aware of to use the bleeding edge of physics as fodder for new propulsion concepts. Without a paradigm shift or two, we're not going any real distances anytime soon.

But I'm not sure if a name and a picture would necessarily be the thing to get the public interested, while it certainly couldn't hurt. Hell, I'm not sure anything could motivate most folks to accept any scientific fact not drilled into them (however erroneously) in grade school. I mean, it's more than two decades since the discovery of Charon, and how many Americans suspect that there aren't just nine planets any more (and, arguably, that there are just eight planets and all sorts of other transneptunian iceballs)?
Put Jupiter in Earth's orbit, and not only Europa, but Ganymede and Callisto suddenly become potential havens for life.

I'm not so sure. That close to the Sun, I think the Jovian satellites would lose much of their mass; so much sunlight would cause their ice to boil away into space, and the rocky cores that remained would be too small to retain an atmosphere.

I suppose a Jovian planet could have a moon made predominantly of rock and metal; I don't know if the processes of planetary formation would encourage or discourage that.
Would a Jovian moon at 1 AU from G-type star really get that hot? Earth goes though periods of glaciation without its ice boiling away into space. There are certainly some massive extrasolar planets that have been discovered that orbit close enough to their stars to be exactly as you describe, but I'm not sure that a Jovian moon in the Goldilocks zone wouldn't just be warm and wet, instead of hot rock. I speak from a position of complete ignorance, though, so I could be entirely wrong.
Earth has a protective atmosphere. If there's any ice on the Moon, it's in spots of permanent shadow, where it's never exposed to sunlight.

Could a Jovian planet have a moon that was the size and composition of the Earth? I have no idea. None of Jupiter's or Saturn's moons come close; is that because the formation of the Jovian planet swept up most of the rock and metal in the area, or was it just chance? I don't know if models of planetary formation are good enough to answer that question.
Atmosphere insulates. Duh. I can only blame seasonal allergies as the reason I forgot my freshman level science curriculum (and the fundamental science behind the greenhouse effect. Jesus).

I'll leave it as a question mark whether Earth-sized Jovian moons are possible. Of course, for the reasons of fiction, I'll probably assume that they are!
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