*** SPAM *** Re: Sirius B (was: Digest V1 #880 then Why I love DWJ)

Jon Noble jon_p_noble at yahoo.com
Fri Sep 17 17:35:01 EDT 2004


--- minnow at belfry.org.uk wrote:

> >Jon
> >> While the only astronomical meaning I know of for
> Zoi
> >> is "zone of influence" (of a comet or star),
> however
> >> the presence of the zoi on earth has left a trace
> as
> >> there is a mineral Zoisite.
> >I don't think I understand the second half of that
> sentence, Jon! Can you
> >explain for an astronomical lunkhead? Actually,
> just how *do* comets
> >influence things? 

All astronomical objects inflence things mostly
through gravity but also though magnetic fields,  or
by falling onto them. Exactly how big an area a ZOI is
is sunject of much discussion. There is an article
about the Sun's ZOI here;

http://antwrp.gsfc.nasa.gov/apod/ap020624.html

"Explanation: Where does the Sun's influence end?
Nobody is sure. Out past the orbits of Neptune and
Pluto extends a region named the heliosphere where the
Sun's magnetic field and particles from the Solar Wind
continue to dominate. The surface where the Solar Wind
drops below sound speed is called the termination
shock and is depicted as the inner oval in the above
computer-generated illustration. It is thought that
this surface occurs as close as 75-90 AU -- so close
that a Pioneer or Voyager spacecraft may soon glide
through it as they exit the Solar System at about 3
AU/year. The actual contact sheet between the Sun's
ions and the Galaxy's ions is called the heliopause
and is thought to occur at about 110 AU. It is
depicted above as the middle surface. The Sun's
heliopause moves through the local interstellar medium
much as a boat moves on water, pushing a bow shock out
in front, thought to occur near 230 AU." (the website
has a pretty picture attached)

 
Like magids? I mean, I know
> people used to believe that
> >(1066 and all that) but what's the modern
> astronomical take?
> 
> I *think* Jon was applying a back-formation: we have
> a mineral called
> Zoisite, therefore the zoi wuz 'ere.

Exactly - the fact that this mineral was discovered by
a geologist called von Zois is nothing but a
remarkable coincidence :)

Jon


		
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