Jupiter: Our Cosmic Protector?

[undeterred]

Jupiter took a bullet for us last weekend.

An object, probably a comet that nobody saw coming, plowed into the giant planet’s colorful cloud tops sometime Sunday, splashing up debris and leaving a black eye the size of the Pacific Ocean. This was the second time in 15 years that this had happened. The whole world was watching when Comet Shoemaker-Levy 9 fell apart and its pieces crashed into Jupiter in 1994, leaving Earth-size marks that persisted up to a year.

That’s Jupiter doing its cosmic job, astronomers like to say. Better it than us. Part of what makes the Earth such a nice place to live, the story goes, is that Jupiter’s overbearing gravity acts as a gravitational shield deflecting incoming space junk, mainly comets, away from the inner solar system where it could do for us what an asteroid apparently did for the dinosaurs 65 million years ago. Indeed, astronomers look for similar configurations — a giant outer planet with room for smaller planets in closer to the home stars — in other planetary systems as an indication of their hospitableness to life.

Anthony Wesley, the Australian amateur astronomer who first noticed the mark on Jupiter and sounded the alarm on Sunday, paid homage to that notion when he told The Sydney Morning Herald, “If anything like that had hit the Earth it would have been curtains for us, so we can feel very happy that Jupiter is doing its vacuum-cleaner job and hoovering up all these large pieces before they come for us.”

But is this warm and fuzzy image of the King of Planets as father-protector really true? “I really question this idea,” said Brian G. Marsden of the Harvard-Smithsonian Center for Astrophysics, referring to Jupiter as our guardian planet. As the former director of the International Astronomical Union’s Central Bureau for Astronomical Telegrams, he has spent his career keeping track of wayward objects, particularly comets, in the solar system. Jupiter is just as much a menace as a savior, he said. The big planet throws a lot of comets out of the solar system, but it also throws them in.

http://www.nytimes.com/2009/07/26/weekinreview/26overbye.html

[RC]

1. Yeah but...

It take 12 Earth years for one Jupiter year. How can it protect us in all those places it isn't and we are?

[Posteritatis]

2. Huge, huge gravitational influence

It sweeps the inner system of stray stuff pretty well, either getting creamed by it instead or hurling it into interstellar space, while keeping a huge amount of what's left over locked into its Trojan clusters. I posted a thread here recently illustrating what it did early in the system's history; it's doing the same thing to the present day.

[izquierdista]

3. That's it, I'm going to become a Jupiter worshiper.

I was wondering what to worship between sunset and sunrise, now I've got it!

[MADem]

4. Ahhh, so Juupiter is a merciful god, and an angry god? How typical! nt

[HamdenRice]

5. The sun is so much bigger, so why don't we see comets & asteroids plunging into it?

Just something I've always wondered. Just since the early 90s we've seen this happen twice with Jupiter.

Or is stuff plunging into the sun and we're just not seeing it? Does it vaporize? Does the sun have a metal core?

[Odin2005]

6. comets plunging into the sun are not uncommon.

There is a class of comets called "Sungrazers" that come within one solar diameter of the sun's surface, most of them are known because of the SOHO spacecraft, but they also include some very famous comets, like the Great Comet of 1843. Small gravitational influences can cause then to fall into the sun.

[HamdenRice]

8. Thanks

Right after I posted that I googled the question and read about star gazers. Apparently, asteroids are also believed to fall into the sun, but because they are dark and vaporize they are invisible to telescopes.

Sun grazers have been observed falling into the sun.

[BlooInBloo]

7. Gravitational magnet is a better term, but whatever.

[L. Coyote]

9. How many hits has the moon taken for the earth?