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View Full Version : Jupiter Our Silent Guardian?



Fraser
2009-Nov-25, 06:40 PM
We live in a cosmic shooting gallery. In Phil Plait's Death From the Skies, he lays out the dangers of a massive impact: destructive shockwaves, tsunamis, flash fires, atmospheric darkening…. The scenario isn't pretty should a big one come our way. Fortunately, we may have a silent guardian: Jupiter. (...)Read the rest of Jupiter – Our [...]

More... (http://www.universetoday.com/2009/11/25/jupiter-our-silent-guardian/)

Buttercup
2009-Nov-25, 07:34 PM
Yep. :) It's been characterized before as our big brother.

George
2009-Nov-25, 08:00 PM
Yep. :) It's been characterized before as our big brother. Do you like your big brother? :)


When the simulation was redone for for short period comets, they again found that, although Jupiter (and the other gas giants) may be effective at removing these dangerous objects, quite often they did so by sending them our way. As such, they again concluded that, as with asteroids, Jupiter's gravitational jiggling was more dangerous than it was helpful.

Why wouldn't the flinging action by Jupiter increase the objects' orbits thereby reducing the number of times it could encounter the Earth?

IsaacKuo
2009-Nov-25, 08:08 PM
Without Jupiter there, the comets which didn't happen to cross Earth's orbital plane at exactly 1AU would never have a chance to hit Earth. Even one pass is greater than zero passes.

George
2009-Nov-26, 04:31 PM
Without Jupiter there, the comets which didn't happen to cross Earth's orbital plane at exactly 1AU would never have a chance to hit Earth. Even one pass is greater than zero passes. But does this mean more comet's have a chance with Jupiter to hit Earth? The atricle's claim seems to say that it's a wash; what is gained by Jupiter batting away dangerous comets is lost by the ones it alters such that they hit Earth.

Argos
2009-Nov-26, 05:05 PM
When the simulation was redone for for short period comets, they again found that, although Jupiter (and the other gas giants) may be effective at removing these dangerous objects, quite often they did so by sending them our way. As such, they again concluded that, as with asteroids, Jupiter's gravitational jiggling was more dangerous than it was helpful.

Well, this increases the chances for the existence of life elsewhere in the galaxy, since it implies that the presence of a giant planet is not needed to 'defend' evolving life in a given stellar system.

IsaacKuo
2009-Nov-26, 05:07 PM
But does this mean more comet's have a chance with Jupiter to hit Earth?
No, it means that you can't tell without performing simulations and calculating things out. That's what these researchers were doing.

George
2009-Nov-27, 02:57 AM
No, it means that you can't tell without performing simulations and calculating things out. I was responding to your idea. I would assume more active comets would be within or close to the plane of the Earth, due to their formation within the accretion disk, as compared to the number not so closely aligned.