The Observant Astronomer

The passing scene as observed by an observant Jew, who daylights as an astronomer.

Friday, May 27, 2005

News from the outer solar system

A Lag B'Omer roundup.

The venerable Voyager 1 spacecraft is now officially on the way out of the solar system. Data in 2002 controversially suggested that it had reached the termination shock where the velocity of the solar wind becomes subsonic as it encounters pressure from interstellar space. Now, new observations from Dec 2004 conclusively show that the spacecraft is now in the heliosheath beyond the termination shock. This now allows scientists to estimate the location of the actual boundary of interstellar space. Voyager 1 may cross this point as soon as 2014. There still will be enough power to send a message back. But, funding for the mission is set to end this year, so no one may be listening.

Who ordered that? Newly released Cassini observations of S1/Titan have identified an odd spot on the surface. This might be some indication of recent geological processes on the surface, but at the moment they're baffled.

Another body that would float: In the 27 May 2005 issue of Science Anderson et al. show, based on Galileo and Voyager data, that JV/Amalthea's density is 857 +/- 99 kg/cubic meter. Ice is 930, and water even more. Unlike Saturn, Amalthea's longest dimension is only 125 km, so there would be no problem finding a body of water large enough to float it in.

Finally, in the historical reconstruction department, Nature published this week a series of papers with a model of how the outer solar system ended up arranged the way it has. The trigger was when the orbits of Jupiter and Saturn briefly entered a 2:1 resonance (2 Jupiter orbits per Saturn one). Resonances are notorious for mixing things up. The result of this one appeared to be to flip Neptune out past Uranus, collecting all sorts of rubbish along the way: Pluto and its companions in the Kuiper belt. What didn't get captured got flung around all over the place, accounting for Jupiter's Trojan companions, and the Late Heavy Bombardment.


Blogger Rebeljew said...

"But funding for the mission is set to end"

I read in Robert Park's newsletter "What's New" that it will only save 4.5M, but that the administration is looking to apply more budget to the manned Moon/Mars initiatives. He feels that is an ill devised scheme as he does not think manned missions will yield anything worth the costs. Agree?

By "Late Heavy Bombardment", do you mean the same event that was mentioned in the kid's Moshiach book, which described an attack on Jupiter that we could view from Earth. That was supposed to be an imminent sign for the coming of Moshiach.

12:37 PM, May 29, 2005  
Blogger The Observer said...

On your first point, see the new posting.

No, you are referring to the impact of Comet P/Shoemaker-Levy 9 on Jupiter in 1994. I've added a link for the LHB.

1:49 PM, May 31, 2005  
Blogger Gregory Anderson said...

this topic is awesome

Producer Chris Young

4:48 AM, February 04, 2013  

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