On Tue, 2 Jun 2009 15:05:26 -0400 Dave Henn <[email protected]> writes: I've posted about the recent discovery that our magnetic field isn't all it's cracked up to be. Here's the post: <http://r-spec.org/node/139>
-- Dave Henn [email protected] This doesn't suprise me greatly. Whenever I hear it said that Mars has a thin atmosphere because of this, no one seems to be able to tel me why Venus (about .78 Earth mass) with virtually no magnetic field, close to the Sun where one migt expect the solar wind to be somewhat more intense and having a higher surface and atmospheric temperature* than Earth, has an atmosphere *denser* than Earth.... * This is important because the rate at which a planet may lose its atmosphere is a function of: 1. The molecular weight of its gases (all other things being equal hydrogen leaves the easiest, CO2 the last, everything else likely to be in a planetary atmosphere is somewhere in between) 2. The temperature at the 'top' of its atmosphere (fast moving 'hot' molecules won't need much more of a kick to escape velocity) 3. And of course, the planet's mass/gravity. Saturn's moon Titan, for example, has a surface presure 1.5 that of Earth sea level, and is less massive than Mars, but it's *cold* that far out, and its atmosphere of nitrogen and methane (IIRC) isn't in a hurry to leave even that fairly shallow gravity well. Venus is surrounded mostly by nice, heavy carbon dioxide, and even at .78 Earth masses, doesn't seem interested in leaving, despite being as hot as a pizza oven at its surface and closer to the Sun... So, I always thought the solar wind vs. planetary magnetic field thing was somewhat overblown. Frank Check out my web page at: http://www.geocities.com/stardolphin2/link3.htm "To be truly radical is to make hope possible, rather than despair convincing." - Raymond Williams ____________________________________________________________ Criminal Lawyers - Click here. http://thirdpartyoffers.juno.com/TGL2141/fc/BLSrjpTOVoIcICPCa1vLFTh75JUZ7HJbRjqe9H9ZnaPnANzzkDmHm5yuho8/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "R-SPEC: The Rochester Speculative Literature Association" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/r-spec?hl=en -~----------~----~----~----~------~----~------~--~---
