HDTenEightyP/NetNews huggingface dataset:
From: scott.smith@the-matrix.com (Scott Smith) 
Newsgroups: sci.astro
Subject: RE: ANY URSID METEORS SEE
Date: 30 Dec 92 10:35:00 GMT
Distribution: world
Organization: The MATRIX BBS - Birmingham, AL - 205-323-2016
Reply-To: scott.smith@the-matrix.com (Scott Smith) 

-> winter stars, and Mars, and in that time I saw two meteors,
-> either of which (but not both) could have been an Ursid.
-> "Back-tracking" both meteors led back to Ursa Major, but to
-> opposite ends of the constellation. As I am sure you know, Ursa Major
-> is *not* a small constellation - so I'd love to know whether I really
-> did spot an Ursid, and if so, which one was it?

Hey, Sharon, I don't know if this message will ever get to you, I don't
trust this network just yet, but I'll give you my input.
I believe that the Ursid meteor shower radiates from close to the
boarder of Ursa Major and Ursa Minor.  So, I guess both of the above
mentioned meteors you saw "could" have been Ursids.  Probably were if
they were coming from the Ursa Minor region.
Ok, I just left my computer to search for an old Astronomical Calendar.
The Ursids do originate from UMi, according to Guy Ottwell, at 14h 28m
+78d, near Kochab (Beta UMi).  I hope that helps.  (I thought it was
Ursa Minor!).

                  *******  Scott  *  Smith  *******
                                                                                                              
Newsgroups: sci.astro,sci.physics
From: bunner@vms.macc.wisc.edu (Dana A. Bunner)
Newsgroups: sci.astro
Subject: Re: binocular question
Date: 29 Dec 92 14:33:47 GMT
Distribution: sci
Organization: University of Wisconsin Academic Computing Center

In article <199228.4258.20565@dosgate>, "michael daly" <michael.daly@canrem.com> writes...

>DA>Most people in their 20's and 30's have a
>DA>maximum eye pupil size of 7mm. 

>You've got it backwards (most people do!).  The seven millimeter exit
>pupil guideline is not the minimum size you should look for, it's the
>maximum.

But I did say maximum.

>DA> Since surface area is a ratio of
>DA>squares, the size of the image will only illuminate about 20% of your
>DA>pupil, wasting 80% of your night sight capability.  16x50's are
>DA>designed as daytime glasses, when your eye contract to about 3 mm.

>If you use an eyepiece exit pupil _larger_ than your eye's
>pupil, some of the light will fall outside of your eye's pupil and will
>be wasted.  If you use an exit pupil smaller than the eye's pupil -
>that's fine; _all_ of the light will be refracted by the eye's lens and
>will illuminate the retina.  You will _not_ lose any of the eye's night
>vision capability.

I believe we are having a difficulty in communicating.  I am in total 
agreement that one should not purchase a binocular which has a larger
exit pupil than your own eye's.  Indeed that would result in wasting a
portion of the image size.

What I was trying to point out that if your eyes do indeed have 7mm
dark light pupils, resulting in pupil surface area of 38.48 sq mm of
surface area, and you illuminated them with a 3.125mm image, or 7.67
sq mm, then you are using just 19.9% of your eye's pupil surface area.
Of course none of the incoming image is being wasted.  Your eyes would
be capable of processing far more light than you are providing to them.

>The image dimness alluded to with higher magnification is not due to the
>small exit pupils - it's due to the fact that you're looking at a
>smaller chunk of sky!

Why then would a 16x80 provide a much brighter image than a 16x50?  And
given that both were designed to cover a 3.5 degree field.

Or if a 10x50 was compared to a 16x50 Wide Angle with both covering a 5
degree field, which would be perceived as brighter?

And would a 25x80 provide approximately the same image brightness as
a 16x50?

I agree with your comments about not necessarily needing 7mm exit pupils.
If someone had just 5.5mm pupils then the surface area of the pupil drops
from 38.48 sq mm to just 23.76 sq mm.  This would also be true if your
primary viewing area is not dark.  Light from nearby street lights might
result in your pupils not expanding to their maximum size.  At this point
one has a dilemma.  It's nice to have those 50mm objectives for light
gathering, yet it is difficult to hold binoculars above 7X steady (for 
many people).  

Dana
From: ref@CS.CMU.EDU (Robert Frederking)
Newsgroups: sci.astro,sci.space,sci.physics,sci.environment
Subject: Solar system stability (Was: averting doom)
Date: 30 Dec 92 17:22:09 GMT
Article-I.D.: cs.C031Kx.7CL.2
Reply-To: ref@cs.cmu.edu (Robert Frederking)
Organization: Center for Machine Translation, Carnegie Mellon University
Originator: ref@DHAKA.MT.CS.CMU.EDU

The latest issue of S&T mentions some recent work done using chaos
theory and large computers to see whether the solar system is stable.
Their finding (I forget who it was now) was that millimeter
perturbations in the orbits of the planets do cause chaotic changes in
the long run.  The good news (for people who don't like chaotic
orbits) is that the amount of time it takes for something ``really
bad'' to become probable is on the order of a trillion years [i.e.,
longer than the solar system will exist in its present form anyway].
``Really bad'' is for a planet to be ejected, a collission, etc.
Newsgroups: sci.astro
From: andromed@cs.dal.ca (Mike Boschat)
Subject: Lunar Eclipse..12/92
Organization: Math, Stats & CS, Dalhousie University, Halifax, NS, Canada
Date: Tue, 22 Dec 1992 19:32:27 GMT


  To me it was not seen with the naked eye, I gave it
a 0/5 on the Dajaon scale...



						Clear skies

						Mike Boschat

                                          andromed@sleet.atm.dal.ca
 ---------------------------------------------------------------------------
|                                   |  "Our problems are man-made,          |
|        JOHN F. KENNEDY            | therefore they can be solved by man " |
|                                   |                                       |
|   ASTRONOMICAL  OBSERVATORY       |                 J.F.K.                |
|                                   |                                       |
 ---------------------------------------------------------------------------
From: billn@hpcvaac.cv.hp.com (bill nelson)
Subject: Re: Averting doom
Organization: Hewlett-Packard Company, Corvallis, Oregon USA
Date: Sun, 27 Dec 1992 10:57:48 GMT

jmc@SAIL.Stanford.EDU (John McCarthy) writes:
: 
:      Also, to move the Earth into a higher orbit, you would not
:      speed the Earth up - you would slow it down.  The Earth
:      orbits the sun about 3 miles/second faster than Mars does.
: 
: This isn't correct.  To move the earth out you speed it up.  This
: makes its orbit a longer ellipse with the perihelion at the point
: where you sped up the earth.  At the aphelion of this orbit the
: earth will indeed be moving more slowly than it was originally.
: In fact if the aphelion is at the distance from the sun of Mars,
: it will be moving more slowly than Mars.  Now another speed-up
: applied at the aphelion can circularize the orbit again.

True - my posting was a misleading. To be in a circular orbit at
a greater radius, the Earth would have to be traveling slower.

Thanks for the correction. It goes to show what posting in the
middle of the night does to a person's brain.

Bill
Newsgroups: sci.astro
From: billn@hpcvaac.cv.hp.com (bill nelson)
Subject: Re: Help please (info on reflectors)
Organization: Hewlett-Packard Company, Corvallis, Oregon USA
Date: Wed, 23 Dec 1992 22:42:42 GMT

rking@acorn.co.uk (Richard King) writes:
: 
: I am a newcomer to astronomy and would be grateful for some
: guidance on a couple of points.
: 
: Firstly I am using a secondhand home built 6" Newtonian telescope
: but have little understanding of how to set up and maintain the 
: instrument.

: Are there any recommended books on this subject ?

A pretty good all around book is the book by Sam Brown - available
from Edmund Scientific. I seem recall that the title is "Building
Your Own Telescope". I can look it up - if you need the exact title.

There is a surprising amount of information in that softcover book.

: What power eyepiece lenses should I be able to use ? (and where in 
: the UK can I buy them from ?)

If the optics, collimation and "seeing" are all perfect - you might
be able to use 60x per inch or (in your case 360x). I would not count
on it. Frequently 30x to 40x per inch is a practical limit. You might
be able to use 300x (50x/inch) on exceptional nights.

The exception is when you are attempting to split close-double stars.
There, you are not interested in fine resolution - all you want to do
is tell that there are two (or more) stars in the group. 

Is the telescope an f8 - with a 48" focal length?  To get magnification,
you divide the focal length of the scope by the focal length of the
eyepiece.  In other words, if you have a 25mm focal length eyepiece
(1 inch), then the magnification of the scope would be 48x. With a 13mm 
eyepiece ( 1/2 inch fl), then the magnification would be 96x.

By the way. Get the best eyepieces that you can afford - assuming that
your telescope optics are reasonable. Good eyepieces make a tremendous
difference in how well the telescope performs. 

Bill
Newsgroups: sci.astro
From: dsmith@hplabsz.hpl.hp.com (David R. Smith)
Subject: Re: Buying mail-order from camera stores
Date: Mon, 21 Dec 1992 18:27:59 GMT
Organization: Hewlett-Packard Laboratories Palo Alto,CA

In article <1992Dec18.201730.17670@athena.cs.uga.edu> mcovingt@aisun3.ai.uga.edu (Michael Covington) writes:
>If you want a good telescope dealer, though, use Orion Telescope Center
>in Santa Cruz, California.

I have patronized Orion a number of times.  I got my first scope from them.
But their price for the TeleVue Plossl is $89, while Shutan is offering 20%
off their normal $79 price.  That is why I asked about Shutan.

-- 
David R. Smith, HP Labs |   "I like to get my hands dirty,
dsmith@hpl.hp.com       |   because it stimulates my mind."
(415) 857-7898          |        -- Irwin Sobel
Newsgroups: sci.astro
From: jmc@SAIL.Stanford.EDU (John McCarthy)
Subject: Re: Averting doom
Reply-To: jmc@cs.Stanford.EDU
Organization: Computer Science Department, Stanford University
Date: 26 Dec 92 23:32:00

Bill Nelson says:


     Also, to move the Earth into a higher orbit, you would not
     speed the Earth up - you would slow it down.  The Earth
     orbits the sun about 3 miles/second faster than Mars does.

This isn't correct.  To move the earth out you speed it up.  This
makes its orbit a longer ellipse with the perihelion at the point
where you sped up the earth.  At the aphelion of this orbit the
earth will indeed be moving more slowly than it was originally.
In fact if the aphelion is at the distance from the sun of Mars,
it will be moving more slowly than Mars.  Now another speed-up
applied at the aphelion can circularize the orbit again.
--
John McCarthy, Computer Science Department, Stanford, CA 94305
*
He who refuses to do arithmetic is doomed to talk nonsense.

Newsgroups: sci.astro,sci.space,sci.physics,sci.environment
From: scip1061@nuscc.nus.sg (Marc Paul Jozef)
Subject: Re: Size of Second-Order GR Effects in Binary Pulsars
Organization: National University of Singapore
X-Newsreader: Tin 1.1 PL4
Date: Wed, 23 Dec 1992 10:30:23 GMT

lip@s1.gov (Loren I. Petrich) writes:
: [marc van loo writes, observing arguments of L.I.P:]
:
: >       So this is the way real scientists reason.
: >       Most impressive.   
: 
: 	Tsk, tsk, tsk. Sarcasm ain't very nice.
: 

       But it does help!
       In your last post, you were finally arguing.

       However, if you are determined to show that
       Tom is rambling, the easiest way is to tell
       us what is wrong with Yu's paper.
       It is only 4 pages long, 1 page intro,
       2 pages conventional GR, and 1 page of actual
       criticism.
Newsgroups: sci.astro
From: billn@hpcvaac.cv.hp.com (bill nelson)
Subject: Re: Averting doom
Organization: Hewlett-Packard Company, Corvallis, Oregon USA
Date: Sun, 27 Dec 1992 20:48:00 GMT

det@bigbootay.sw.stratus.com (David Toland) writes:
: In article <1992Dec27.070033.18932@hpcvaac.cv.hp.com> billn@hpcvaac.cv.hp.com (bill nelson) writes:
: >Also, to move the Earth into a higher orbit, you would not speed the
: >Earth up - you would slow it down.  The Earth orbits the sun about
: >3 miles/second faster than Mars does. 
: 
: A little knowledge.....
: 
: Although the velocity of Mars along its orbital path *is* lower, its
: angular momentum is higher.  You would indeed need to *increase* the
: Earth's velocity in its present orbit, which would paradoxically result
: in it attaining a greater distance from the Sun with a *lower*
: orbital speed.  The increase in speed would need to be applied over
: a multiple of 1 revolution if you want the final orbit to also remain
: nearly circular.

Yes - I am aware of this. I was just not thinking, at the time I made
the posting. Shows what happens when a person posts, at a time which is
long past their bed-time.

: By the way, Niven's enginering, although not perfect, stands up better
: than that of *most* SF writers...

Agreed. I enjoy his writing.

Bill
From: pcl@ox.ac.uk (Paul C Leyland)
Newsgroups: sci.astro
Subject: Re: Purchasing Amateur Telescopes: Spherical Aberrations
Date: 21 Dec 92 10:10:39 GMT
Organization: Oxford University Computing Services, 13 Banbury Rd Oxford OX2
	6NN
In-reply-to: chaloux@mandolin.mitre.org's message of 15 Dec 92 17:37:42 GMT

In article <1992Dec15.173742.21242@linus.mitre.org> chaloux@mandolin.mitre.org (Dave Chaloux) writes:

   The following occurs in the FAQ.

   >spherical aberration
   >     A problem where a spherical lens or mirror in a telescope is  not
   >     shaped  correctly,  so  the light from the center is focused at a
   >     different location than the light from  the  edges.   You  should
   >     never  have  to  worry  about this.  This only shows up in really
   >     cheap telescopes, like the Hubble Space Paperweight.

...

   For some uses 1/2 wave optics may in fact be good enough. For example if
   you were buying a 13" F4.5 mirror and knew you were only going to be
   using it at a maximum of 130x and you also knew you were the kind of
   person that won't bother to accurately collimate the optics anyway maybe
   you would settle for this (and maybe not. I can think of reasons not to).

I own a 18" F4.5 with significant spherical aberration.  Don't know
how bad it is in terms of 1/n wave, but star images are about 1.5
arcseconds across.  It would be nice if it were better, but I'm not
too bothered.  It's used only as a light-bucket.  So long as the stars
are sharp enough for me to make a good estimate of their magnitude,
that's fine.  I'm certainly not going buy a mirror at twice the price,
just so I can peer at a couple of planets 8-)

It is a cheap (i.e. inexpensive) telescope.  That's the whole idea --
lowest magnitude reach within a fixed budget.  Now, when I get around
to building the photoelectric photometry bits ...


Paul

--
Paul Leyland <pcl@oxford.ac.uk>          | Hanging on in quiet desperation is
Oxford University Computing Service      |     the English way.
13 Banbury Road, Oxford, OX2 6NN, UK     | The time is come, the song is over.
Tel: +44-865-273200  Fax: +44-865-273275 | Thought I'd something more to say.
Finger pcl@black.ox.ac.uk for PGP key    |
Newsgroups: sci.astro
From: jack@switchview.com
Subject: Purchasing a Newtonian Reflector
Organization: SwitchView Inc
Date: Tue, 29 Dec 1992 20:49:52 GMT

I am interested in purchasing a telescope and I've been reading this news
group for the past few weeks.  I've read the FAQ and they helped me start 
on the road to deciding what I should buy.

With budgeting in mind I've decided that a 4 1/2 Newtonian Reflector
will be a good start.  This is where my difficulty begins.  

The telescope shop that I visited in Toronto had three 4 1/2inch Reflectors 
to choose from : The Vixen, Meade and Celestron.  They range in price from 300$ 
(for the Vixen with the Alt-Az mount)  to  650$ ( for the Celestron the the 
equitorial mount). That's Canadian dollars. 

I'd like to know how different these three models are optically.  I understand
that the quality of the mounts may differ and that they come with different 
eye pieces and finder scopes.  Will the images that I see through the 
Celestron be significantly different than the images that I see through the
Vixen?  

Has anyone used the Vixen 4 1/2inch reflector or the new Meade 4500? 

Any comments would be greatly appreciated.

Jack Kesselman
SwitchView Technical Support
jack@switchview.com



Newsgroups: sci.astro,rec.radio.shortwave
From: oler@rho.uleth.ca (Cary Oler)
Subject: Daily Solar Geophysical Data Broadcast for 29 December
Organization: University of Lethbridge
Date: 30 Dec 92 08:08:03 GMT

!!BEGIN!! (1.0) S.T.D. Solar Geophysical Data Broadcast for DAY 364, 12/29/92
10.7 FLUX=125.1  90-AVG=139        SSN=110      BKI=5655 4432  BAI=037
BGND-XRAY=B2.8     FLU1=3.1E+05  FLU10=1.1E+04  PKI=5565 5533  PAI=042
  BOU-DEV=079,121,106,081,046,066,026,015   DEV-AVG=067 NT     SWF=00:000
 XRAY-MAX= C2.6   @ 1721UT    XRAY-MIN= B2.5   @ 0331UT   XRAY-AVG= B4.4
NEUTN-MAX= +001%  @ 2345UT   NEUTN-MIN= -003%  @ 2010UT  NEUTN-AVG= -0.7%
  PCA-MAX= +0.1DB @ 0910UT     PCA-MIN= -0.4DB @ 1125UT    PCA-AVG= -0.0DB
BOUTF-MAX=55426NT @ 0116UT   BOUTF-MIN=55386NT @ 1715UT  BOUTF-AVG=55401NT
GOES7-MAX=P:+108NT@ 2040UT   GOES7-MIN=N:-031NT@ 1139UT  G7-AVG=+052,+043,+009
GOES6-MAX=N:+138NT@ 0851UT   GOES6-MIN=N:-038NT@ 0124UT  G6-AVG=+073,+003,+052
 FLUXFCST=STD:120,120,115;SESC:120,120,115 BAI/PAI-FCST=015,015,010/020,015,010
    KFCST=3334 4333 2212 3111  27DAY-AP=009,012   27DAY-KP=3333 2221 2423 3322
 WARNINGS=*GSTRM;*AURMIDWCH
   ALERTS=**MINSTRM
!!END-DATA!!
Newsgroups: sci.astro,sci.space,sci.physics,sci.environment
From: pg@sanitas.stortek.com (Paul Gilmartin)
Subject: Re: Solstice Question (simple)
Organization: Storage Technology Corp.
X-Newsreader: TIN [version 1.1 PL7]
Date: Thu, 24 Dec 1992 16:11:25 GMT

Andy Goris (goris@hpfcso.FC.HP.COM) wrote:
: 
: I have a simple question for some astronomy guru out there:
: 
:    As everyone knows, winter solstice is the day with the shortest time 
:    between sun-rise and sun-set.  However, it is neither the day
:    of latest sun-rise nor earlist sun-set.  Why is this? ... 
:    ... I can't
:    see how our elliptical orbit could cause this effect.

:    ... I understand how the earths tilt 
:    causes the up-down movement in the figure-8, but what causes the 
:    left-right movement, and why does it have a period of twice/year?

OK.  Get out your globe and your dividers.  Your traditional globe has a
dotted line circling it, inclined to the equator, and marked with calendar
dates indicating the position on the earth directly under the sun (always
with the earth in the same orientation with respect to the remote stars.)
The sun traverses this circle at nearly a constant rate.  However, at its
northern extreme in June and its southern extreme in December, it's
crossing meridians of longitude slightly closer together than at
the equator, so its eastward movement is faster than average.  On the
other hand, when the sun crosses the equator in March and September, it's
crossing meridians that are farther apart, and it's crossing them at
an angle rather than moving directly between them, so its effective
eastward motion is slower than average.

The eccentricity of the earth's orbit does have an effect.  In January,
the earth is the apparent eastward speed of the sun, and makes the
bottom of the figute-8 fatter than the top.

:    1. If you live on the equator, is the length of the day always ~12 hours?

How exact do you mean by "~"?  Because of the effects discussed above, in
June and December the day and night are _both_ >12 hours; in March and
September the day and night are _both_ <12 hours.  On any given date, the
day and night are very nearly equal.
 
:    2. If you live on the equator, do you really get effectively two
:       summers (when the sun is highest in the sky), that occur on the
:       two equinoxes?  

Certainly, as far as position of the sun.  I don't know how noticeably
this might affect the weather.  Has anyone out there in Quito or Nairobi
or Singapore noticed whether it's been chilly this month?  :-)
From: jsmill01@ulkyvx.louisville.edu
Newsgroups: sci.astro
Subject: Re: Future life on Mars?
Date: 29 Dec 92 16:23:10 GMT
Organization: University of Louisville

In article <1992Dec29.153041.14481@athena.mit.edu>, acgoldis@athena.mit.edu (Andrew C Goldish) writes:
>   Since everyone has been discussing the end of life on Earth over the past
> few days, I was wondering whether or not life will be able to arise on Mars,
> at least for a short period of time, during the last one or two billion years
> of the solar system.

[etc.]

> Can the increased heat
> from the sun melt enough ice cap and permafrost water and kick enough CO2
> into the atmosphere to make oceans and turn Mars into a habitable planet
> (at least in the oceans)?
> 						A. Goldish
============================================================================
Unless there is life there now or was in the past, when it is possible 
that Mars may have had more liquid water on its surface, then it is 
possible that we will be the first life on Mars.

As to life arising on Mars in the future as the Sun warms (I didn't 
follow that particular thread, and am leaning more to the increased 
luminosity of the Sun being due to its increased size as it becomes a 
red giant), first, one needs to have a thicker atmosphere.  At 
approximatel 0.01 atm, water would evaporate almost as soon as it 
formed.  Additional vulcanism on the part of Mars would be necessary, 
and I have not seen anything that would indicate that would happen if 
the Sun were more luminous.  And, it is possible that as a red giant, 
the surface of the sun would be much closer to Mars, if Mars is not 
inside itself (have read many different possiblities here), which 
again might make for difficulties.

So, what about the gas giants?

Scott Miller, Program Coordinator
Rauch Memorial Planetarium
University of Louisville
jsmill01@ulkyvx.louisville.edu
Newsgroups: sci.astro,rec.radio.shortwave
From: oler@rho.uleth.ca (Cary Oler)
Subject: Daily Solar Geophysical Data Broadcast for 22 December
Organization: University of Lethbridge
Date: 23 Dec 92 06:21:03 GMT

!!BEGIN!! (1.0) S.T.D. Solar Geophysical Data Broadcast for DAY 357, 12/22/92
10.7 FLUX=142.1  90-AVG=138        SSN=125      BKI=1113 2111  BAI=005
BGND-XRAY=B4.1     FLU1=2.7E+06  FLU10=1.0E+04  PKI=1123 3221  PAI=007
  BOU-DEV=006,006,009,025,019,009,007,005   DEV-AVG=010 NT     SWF=00:000
 XRAY-MAX= C1.7   @ 1451UT    XRAY-MIN= B3.4   @ 2109UT   XRAY-AVG= B4.9
NEUTN-MAX= +002%  @ 1910UT   NEUTN-MIN= -002%  @ 0355UT  NEUTN-AVG= +0.1%
  PCA-MAX= +0.1DB @ 0610UT     PCA-MIN= -0.3DB @ 0950UT    PCA-AVG= -0.0DB
BOUTF-MAX=55426NT @ 1536UT   BOUTF-MIN=55399NT @ 1834UT  BOUTF-AVG=55415NT
GOES7-MAX=P:+106NT@ 2043UT   GOES7-MIN=N:+002NT@ 1258UT  G7-AVG=+080,+029,+009
GOES6-MAX=P:+127NT@ 2043UT   GOES6-MIN=E:-012NT@ 2358UT  G6-AVG=+099,-003,+035
 FLUXFCST=STD:140,140,135;SESC:140,140,135 BAI/PAI-FCST=005,005,015/010,010,015
    KFCST=1123 4321 1123 4321  27DAY-AP=013,009   27DAY-KP=2224 4222 2413 2221
 WARNINGS=
   ALERTS=
!!END-DATA!!
From: pg@sanitas.stortek.com (Paul Gilmartin)
Newsgroups: sci.astro
Subject: Is P/Swift-Tuttle a Record Breaker?
Summary: What long period comets have been observed on multiple apparitions?
Keywords: comet period record apparition
Date: 22 Dec 92 16:23:58 GMT
Organization: Storage Technology Corp.
X-Newsreader: TIN [version 1.1 PL7]

What comets having longer period than P/Swift-Tuttle have been observed
on multiple apparitions?  The decade uncertainty in the prediction of S-T's
current apparition and the difficulty of identifying its 1737 apparition
suggest that there might be very few.
From: tonya@hpldsla.sid.hp.com (Tony Arnerich)
Date: Mon, 21 Dec 1992 21:16:28 GMT
Subject: Re: Buying mail-order from camera stores
Organization: HP Scientific Instruments Division - Palo Alto, CA