Re: OFFLIST: Galactic Year: (was: Re: Reviving an old tradition)
| From: | Nomad of Norad -- David C Hall <nomad-conlang@...> |
|---|
| Date: | Saturday, February 11, 2006, 20:51 |
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Hi tomhchappell (tomhchappell), in <dslfpa+ph34@...> on Feb 11 you wrote:
> Hi, Henrik.
>
> --- In conlang@yahoogroups.com, Henrik Theiling <theiling@...> wrote:
> >
> >Hi!
> >
> >Larry wrote:
> >>>>The modern/space-age section would include terms like [snip]
> >>>>galactic year [snip]
> >>>
> >>>What's a galactic year?
> >>>
> >>
> >>The time it takes for the galaxy to revolve once about its axis.
> >>Some hundreds of millions of years, I forget exactly. --larry
>
> Unfortunately this "definition" defines nothing, because galaxies are
> not rigid objects and do not "revolve" as a unit about their axes.
> (If they did, "rotate" would be the word to use.)
Funny thing is, when I saw this message coming in (my current mail
collecting system displays the From: Subject: and To: lines of each
message to screen as it collects it) and saw "Galactic Year" in it,
my first thought was my own usage of the term Galactic Year in a
space-opera universe I helped create. (See my .sig! :-D )
In that system, though, "Galactic Year" was shorthand for "Galactic
Standard Year," and basically meant "this is the year-system that the
various Human planets have standardized themselves to all across the
galaxy..." and is roughly the same length as one Earth year.
It was usually rendered "It is the year 2379 Galactic."
> (By analogy if you tried to define a "solar day" as the length of
> time it takes the Sun to "rotate" around its axis, you'd get
> different answers at the solar poles than at the solar equator. The
> sun's equator spins around its axis faster than its poles do; this
> tangles up its magnetic field lines something fierce, and
> straightening them out involves lots of prominences and sunspots and
> flares etc.)
Star Trek occasionally uses the term "Solar day" and even "Solar minute"
and whatnot, but apprently it meant "One Earth day" and "one Earth minute"
respectively, and since Earth is in the Sol system the writers probably
figured "Solar" (read "of the Sol system") time and "Earth" time could
be used interchangeably...
They stopped doing it after The Original Series, though. Probably too
many space-science people complained. :-D
> Different layers of a galaxy revolve in different periods; the stars
> closer in take less time to revolve around the galactic center, the
> stars further out take more time to revolve around the galactic
> center.
>
> (BTW the orbits are ordinarily elliptical rather than circular, and
> they precess at different rates, too. If the long axes of these
> elliptical orbits are all parallel, the galaxy looks neat and
> organized; a while later, after the ones closer in have turned at a
> different rate than the ones further out, the galaxy looks spiral.)
>
> You could define a "galactic year" as the length of time it takes
> _our_ star to revolve around _our_ galaxy's center. That would have
> a definite meaning at each star, but would probably change when you
> moved to a different star -- probably not by much as long as the two
> stars were close to each other and in the same "Population".
>
> >
> >Simple learn the Galaxy Song from Monty Python's Meaning of Life by
> >heart :-):
> >
> >...
> >We're thirty thousand light years from galactic central point,
> >we go round every two hundred million years.
>
> Thanks.
>
> _We_ go around once every two-hundred-million years.
>
> Stars closer in to the center take less time to go around;
> stars further out from the center take more time to go around.
>
> >...
> >
> >BTW, some funny pedant has checked the propositions from the song:
> >
> >
http://ephemeris.sjaa.net/0312/b.html
>
> Thanks.
>
> >
> >:-))))
> >
> >**Henrik
> >
>
>