Xref: utzoo talk.politics.misc:8580 sci.misc:1165 Path: utzoo!mnetor!uunet!husc6!think!bloom-beacon!athena.mit.edu!jfc From: jfc@athena.mit.edu (John F Carr) Newsgroups: talk.politics.misc,sci.misc Subject: Re: Darren Leigh at the Edge of Space: Part II Message-ID: <4062@bloom-beacon.MIT.EDU> Date: 26 Mar 88 08:23:51 GMT References: <3405@bloom-beacon.MIT.EDU> <3884@whuts.UUCP> <2177@mit-amt.MEDIA.MIT.EDU> <4010@whuts.UUCP> Sender: daemon@bloom-beacon.MIT.EDU Reply-To: jfc@athena.mit.edu (John F Carr) Organization: Massachusetts Institute of Technology Lines: 90 In article <4010@whuts.UUCP> orb@whuts.UUCP (45263-SEVENER,T.J.) writes an article perhaps more appropriate for rec.humor, and fails to apologize to me for his accusations that I copied the magnitude of refraction out of a book that I did not understand, despite the fact that I derived that value (which Tim has admitted is correct) in an article in this newsgroup: : This issue, like many on the Net, has been hashed out a long : time ago. George Stoney wrote a classic paper examining the : content of the atmosphere at the edge of space, and for various ^^^^^^^^^^^^^^^^^^^^ What edge? : planets and satellites. This paper was republished in the : book, "A Source Book in Astronomy and Astrophysics, 1900-1975". ^^^^^^^^^ : Mr. Stoney correctly predicted many years before space travel ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ : the composition of gases in various planetary atmospheres. You mean, Tim, that you are quoting as a source on the upper atmosphere a speculative paper that was written before anyone actually measured its properties? Can I quote in return from the classic work by J. Verne, titled _From_the_Earth_to_the_Moon_ which makes many predictions of conditions far above the Earth? : Anyway, let me note a quote from p.90 of "A Source Book": : "...From this point upwards the density of : the atmosphere will decrease by a much more rapid law, : which will, within a short space, bring the atmosphere to : an end." : Got that, Mr. Leigh? : "within a short space, bring the atmosphere to an end." The rest of us realize that this is not true. Certainly NASA would be surprised to learn that it was impossible for Skylab to fall, or for the orbit of the LDEF to decay. At what altitude, Tim, do you claim that the atmosphere ends? Are you aware of the fact that nowhere is there a true vacuum, and that the Earth's atmosphere smoothly fades into the solar atmosphere (or solar wind)? : Of course, I realize that the geniuses on this Net know : better than the Britannica Micropedia or a source book on : classic papers on Astronomy and Astrophysics, so I don't ^^^^^^^ In other words, old. A lot of people know better now than did those scientists. I once read a book on astrophysics written between 1900 and 1975 (closer to the earlier date) which speculated on the energy sources of stars. Interesting reading, and rather amusing to one knowing about nuclear reactions. Also now recognized as wrong. It was about the best they could do with the knowledge available. Similarly, without measuring the upper atmosphere, its properties can only be guessed at. The guess posted by Tim is a wrong guess. The scale height may decrease at high altitude (though I suspect the opposite, since the temperature is so high: I'll check the CRC) but the atmosphere does not end. : suspect this will persuade them. Tim: you refused to accept the astronomy references I used, or the relevance of the fact that I am studying astronomy (and astrophysics). Will you now do that? If you do not accept the validity of my astronomy references on the grounds of irrelevance, don't post your own. I could also quote from the lecture notes of a course I am taking on celestial mechanics, the current topic of which is low earth orbits. We just spent several lectures examining the effects of atmospheric drag. I am relieved to learn that the abrupt end of the atmosphere has made it unnecessary to remember any of this. A more appropriate source would be one of the standard atmospheres. See, for example, the Handbook of Chemistry and Physics. ("But," I hear Tim preparing to write, "that book is published by a corporation so it must be biased.") That has extensive tables of atmospheric properties to several hundred km altitude. If you look very carefully at the tables (if the tables are too complicated for him, Tim can look at the drawings instead) you will fail to notice any sudden drop in pressure or density. John Carr "No one wants to make a terrible choice jfc@athena.mit.edu On the price of being free" -- Neil Peart