Saturday, July 25, 2009

By Jove

A week ago, scientists noticed a black spot on Jupiter. Apparently the gas giant was struck by a sizable asteroid or comet. CosmicLog has the details. Jupiter functions as a guard for the inner solar system, deflecting asteroids and comets out of Earth's path. Were it not for Jupiter, the Earth would be struck by asteroids a thousand times more frequently, enough to prevent the possibility of advanced life evolving. Or to put it the other way round, in order for advanced life to exist on a planet, its solar system will require a planet the size and distance of Jupiter. If it were smaller or further, it wouldn't have enough gravitational impact to protect the inner planets; but if it were closer or larger, its gravitational effects would disrupt their orbits. It has to be exactly the size and distance it is. This is one criterion of the Anthropic Principle. Thank God for Jupiter.

That's the good news. The bad news is that we're still vulnerable and need to take the threat of an asteroid strike seriously. Part of the story here is that no one saw this asteroid before it hit Jupiter. It was a complete surprise. Of course we don't have as many electronic eyes out there as we do closer to home; but to give Jupiter as big of a black eye as it did, it must have been big enough so that it should have been seen beforehand. It's only a matter of time before something that big comes our way.

I know some people will not take seriously the claim that the Earth is in danger of being hit with a large asteroid or comet. It doesn't happen that often, it's just a doomsday scenario, etc. I'm reminded of a Dilbert cartoon about pessimists and optimists. If it's been a long time since anything bad has happened (an asteroid strike in this case), the optimist says, "We're safe forever." The pessimist says, "We're due."

(cross-posted on Quodlibeta)

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