Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT/SPACEDIG/V16_4/V16NO496.TXT

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Date: Wed, 28 Apr 93 05:21:59
From: Space Digest maintainer <[e-mail]>
Reply-To: [e-mail]
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)

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----------------------------------------------------------------------

Date: Tue, 27 Apr 93 13:16:18 BST
From: Greg Stewart-Nicholls <[e-mail]>
Subject: Death and Taxes (was Why not give $1 billion to...
Newsgroups: sci.space

In <[e-mail]> 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
[e-mail] or     : Vici
[e-mail] : Veni

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Date: Tue, 27 Apr 93 03:17:48 GMT
From: Keith Harwood <[e-mail]>
Subject: Gamma Ray Bursters. WHere are they.
Newsgroups: sci.astro,sci.space

In article <[e-mail]>, [e-mail] (David M. Palmer) writes:
> [e-mail] (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.

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Date: 27 Apr 93 13:52:19
From: "Jonathan P. Gibbons" <[e-mail]>
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"

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Date: Tue, 27 Apr 1993 13:38:28 GMT
From: Doug Loss <[e-mail]>
Subject: What planets are habitable
Newsgroups: sci.space

In article <[e-mail]> [e-mail] (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
[e-mail]

------------------------------

Newsgroups: sci.space

From: "Gregory N. Bond" <[e-mail]>
Subject: Re: Death and Taxes (was Why not give $1 billion to...
In-Reply-To: [e-mail]'s message of 22 Apr 93 16:25:01 -0500
Message-Id: <[e-mail]>
Sender: news READER id <[e-mail]>
Nntp-Posting-Host: baby
Organization: Burdett, Buckeridge & Young, Melbourne, Australia
References: <[e-mail]>
Date: Tue, 27 Apr 1993 07:25:12 GMT
Lines: 17
Source-Info:  Sender is really [e-mail]
Source-Info:  Sender is really [e-mail]

In article <[e-mail]> [e-mail] 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 <[e-mail]> 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" <[e-mail]>
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: <[e-mail]>
References: <1radsr$[e-mail]> <[e-mail]>
    <[e-mail]>
Reply-To: [e-mail]
Nntp-Posting-Host: seti.tn.cornell.edu
Summary: Galaxy is transparent.
Keywords: Galaxy - gamma rays
In-Reply-To: [e-mail]'s message of 26 Apr 1993 15:37:32 GMT
Sender: [e-mail]
Source-Info:  Sender is really [e-mail]

>>>>> On 26 Apr 1993 15:37:32 GMT, [e-mail] (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 ( [e-mail] ) 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: [e-mail]
   T. Joseph Lazio       | phone:  [phone]
                         | ICBM:   42 deg. 20' 08" N  76 deg. 28' 48" W
Cornell knows I exist?!? |       STOP RAPE

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End of Space Digest Volume 16 : Issue 496
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