Sunday, July 26, 2009

By Jove

A week ago, scientists noticed a black spot on Jupiter. Apparently the gas giant was struck by a sizable asteroid. 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 Agent Intellect)

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Humphrey said...

It's a bit of a double edged sword according to this study.

On the one hand Jupiter appears to provide protection from external comets and other objects. On the other hand it's gravitational field stirs up the asteroid belt and redirects some objects towards the earth (although most of them are very small). Luckily the solar system is so diffuse that serious impacts are extremely rare (although the Tunguska Event may have been as high as 10-15 megatonnes). The last really significant one was 65 million years ago.

Humphrey said...

Of course, being hit by comets is not automatically a bad thing. See here for instance:

It helps not to be in the way of course.

Humphrey said...

Some more support for the Jupitar and Saturn as Guardian planets theory.