Date: Wed, 28 Apr 93 05:21:59 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #496 To: Space Digest Readers Precedence: bulk Space Digest Wed, 28 Apr 93 Volume 16 : Issue 496 Today's Topics: Death and Taxes (was Why not give $1 billion to... Gamma Ray Bursters. WHere are they. What planets are habitable (2 msgs) Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: Tue, 27 Apr 93 13:16:18 BST From: Greg Stewart-Nicholls Subject: Death and Taxes (was Why not give $1 billion to... Newsgroups: sci.space In <1993Apr27.072512.439@bby.com.au> Gregory N. Bond writes: >I wouldn't even begin to expect that >in Australia, and we don't have institutionalised corruption like you >do. Wanna bet ??? You must be too young to remember Bob Askin :-) Read the Costigan commision report if you want to know about corruption in OZ. ----------------------------------------------------------------- Greg Nicholls ... : Vidi nicho@vnet.ibm.com or : Vici nicho@olympus.demon.co.uk : Veni ------------------------------ Date: Tue, 27 Apr 93 03:17:48 GMT From: Keith Harwood Subject: Gamma Ray Bursters. WHere are they. Newsgroups: sci.astro,sci.space In article <1rbl0eINNip4@gap.caltech.edu>, palmer@cco.caltech.edu (David M. Palmer) writes: > prb@access.digex.com (Pat) writes: > > > What evidence indicates that Gamma Ray bursters are very far away? > > >Given the enormous power, i was just wondering, what if they are > >quantum black holes or something like that fairly close by? > > >Why would they have to be at galactic ranges? > . . . David gives good explaination of the deductions from the isotropic, 'edged' distribution, to whit, they are either part of the Universe or part of the Oort cloud. Why couldn't they be Earth centred, with the edge occuring at the edge of the gravisphere? I know there isn't any mechanism for them, but there isn't a mechanism for the others either. Keith Harwood. ------------------------------ Date: 27 Apr 93 13:52:19 From: "Jonathan P. Gibbons" Subject: What planets are habitable Newsgroups: sci.space I would appreciate any thoughts on what makes a planet habitable for Humans. I am making asumptions that life and a similar atmosphere evolve given a range of physical aspects of the planet. The question is what physical aspects simply disallow earth like conditions. eg Temperature range of 280K to 315K (where temp is purely dependant on dist from the sun and the suns temperature..) Atmospheric presure ? - I know nothing of human tolerance Planetary Mass ? - again gravity at surface is important, how much can human bodies take day after day. Also how does the mass effect atmosphere. I thinking of planets between .3 and 3 times mass of the earth. I suppose density should be important as well. Climate etc does not concern me, nor does axial tilt etc etc. Just the above three factors and how they relate to one another. Jonathan -- ---------------------------------------------------------------------------- With fearsome eyes and fiery breath the dragon burnt the girl to death -- from "Too Late Saint George" ------------------------------ Date: Tue, 27 Apr 1993 13:38:28 GMT From: Doug Loss Subject: What planets are habitable Newsgroups: sci.space In article jpg@bnr.co.uk (Jonathan P. Gibbons) writes: >I would appreciate any thoughts on what makes a planet habitable for Humans. >I am making asumptions that life and a similar atmosphere evolve given a range >of physical aspects of the planet. The question is what physical aspects >simply disallow earth like conditions. > >eg Temperature range of 280K to 315K (where temp is purely dependant on dist > from the sun and the suns temperature..) > Atmospheric presure ? - I know nothing of human tolerance > Planetary Mass ? - again gravity at surface is important, how much > can human bodies take day after day. Also how does the mass effect > atmosphere. I thinking of planets between .3 and 3 times mass of the > earth. I suppose density should be important as well. > >Climate etc does not concern me, nor does axial tilt etc etc. Just the above >three factors and how they relate to one another. > Dandridge Cole and Isaac Asimov collaborated on a book titled, "Habitable Planets for Man" (I think) in 1964. It should be available in most good libraries, or through inter-library loan. It answered the questions you ask (speculatively, of course), along with many more that need to be considered in habitability studies: length of day (for day/night temperature variation, and agricultural concerns), partial pressures of certain unexpected gasses (ever hear of xenon narcosis? neither did I), density of particulates in the atm, and their composition (ever hear of silicosis? not much fun), etc. Climate isn't a global phenomenon and probably needn't concern you, but axial tilt ought to. It plays a large part in determining the severity of seasonal differences, and a lesser but still significant part in determining the speed of prevailing winds. Doug Loss loss@husky.bloomu.edu ------------------------------ Newsgroups: sci.space From: "Gregory N. Bond" Subject: Re: Death and Taxes (was Why not give $1 billion to... In-Reply-To: tffreeba@indyvax.iupui.edu's message of 22 Apr 93 16:25:01 -0500 Message-Id: <1993Apr27.072512.439@bby.com.au> Sender: news READER id Nntp-Posting-Host: baby Organization: Burdett, Buckeridge & Young, Melbourne, Australia References: <1993Apr22.162501.747@indyvax.iupui.edu> Date: Tue, 27 Apr 1993 07:25:12 GMT Lines: 17 Source-Info: Sender is really news@CRABAPPLE.SRV.CS.CMU.EDU Source-Info: Sender is really isu@VACATION.VENARI.CS.CMU.EDU In article <1993Apr22.162501.747@indyvax.iupui.edu> tffreeba@indyvax.iupui.edu writes: ... So how about this? Give the winning group (I can't see one company or corp doing it) a 10, 20, or 50 year moratorium on taxes. You are talking about the bozos who can't even manage in November to keep promises about taxes made in October, and you expect them to make (and keep!) a 50-year promise like that? Your faith in the political system is much higher than mine. I wouldn't even begin to expect that in Australia, and we don't have institutionalised corruption like you do. -- Gregory Bond Burdett Buckeridge & Young Ltd Melbourne Australia Knox's 386 is slick. Fox in Sox, on Knox's Box Knox's box is very quick. Plays lots of LSL. He's sick! (Apologies to John "Iron Bar" Mackin.) ------------------------------ From: "T. Joseph Lazio" Newsgroups: sci.space,sci.astro Subject: Re: Gamma Ray Bursters. WHere are they. Date: 27 Apr 93 09:04:25 Organization: Department of Astronomy, Cornell University Lines: 29 Message-Id: References: <1radsr$att@access.digex.net> <1rgvjsINNbhq@senator-bedfellow.MIT.EDU> Reply-To: lazio@astrosun.tn.cornell.edu Nntp-Posting-Host: seti.tn.cornell.edu Summary: Galaxy is transparent. Keywords: Galaxy - gamma rays In-Reply-To: jfc@athena.mit.edu's message of 26 Apr 1993 15:37:32 GMT Sender: news@CRABAPPLE.SRV.CS.CMU.EDU Source-Info: Sender is really isu@VACATION.VENARI.CS.CMU.EDU >>>>> On 26 Apr 1993 15:37:32 GMT, jfc@athena.mit.edu (John F Carr) said: jfc> If gamma ray bursters are extragalactic, would absorption from the jfc> galaxy be expected? How transparent is the galactic core to gamma jfc> rays? and later... >>>>> Jim Batka ( JBATKA@DESIRE.WRIGHT.EDU ) said JB> So, if the 1/r^2 law is incorrect (assume JB> some unknown material [dark matter??] inhibits Gamma Ray propagation), JB> could it be possible that we are actually seeing much less energetic JB> events happening much closer to us? The even distribution could JB> be caused by the characteristic propagation distance of gamma rays JB> being shorter then 1/2 the thickness of the disk of the galaxy. 0. Well, maybe not zero, but very little. At the typical energies for gamma rays, the Galaxy is effectively transparent. Hans Bloemen had a review article in Ann. Rev. Astr. Astrophys. a few years back in which he discusses this in more depth. -- | e-mail: lazio@astrosun.tn.cornell.edu T. Joseph Lazio | phone: (607) 255-6420 | ICBM: 42 deg. 20' 08" N 76 deg. 28' 48" W Cornell knows I exist?!? | STOP RAPE ------------------------------ End of Space Digest Volume 16 : Issue 496 ------------------------------