Why Are There Galaxies?

In message
, Painius
writes

Say "hi" to Rod Serling for me, and i have a sillyass gut
feeling that people are underestimating the brightness
of our Galaxy Central by several increments. "Sillyass"
because there is unfortunately no way to be certain.

And i know just as sure as i know how to pound these
keys that the hub of the Milky Way Galaxy is bright
enough to rival the Sun!


You're being unduly influenced by the end of "The Empire Strikes Back",
and by all those pictures that show the centre of a galaxy as dazzling.
Don't forget that the first is fiction and the second is the result of
integrating the light over minutes to hours.
OTOH, consider the view from a star about a thousand light years from
the centre. I suspect that would be truly spectacular, though I'll leave
it to an artist like Ron Miller to work out the details and do it
justice.
--
Rabbit arithmetic - 1 plus 1 equals 10
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"Painius" wrote in message ...


Say "hi" to Rod Serling for me, and i have a sillyass gut
feeling that people are underestimating the brightness
of our Galaxy Central by several increments. "Sillyass"
because there is unfortunately no way to be certain.

And i know just as sure as i know how to pound these
keys that the hub of the Milky Way Galaxy is bright
enough to rival the Sun!


I would hope you type better than that Panius :-). No, it wouldn't
even come close to rivaling the sun's brightness unless, perhaps, if
you were observing the hub from, say, around 1000 light years or so of
the center. Even then, the brightness would be spread over a huge
area of the sky, so while you would see a *lot* of stars and much of
the sky would probably seem to be glowing, it wouldn't quite be like
having the sun up. The brightness of the core region can be quite
easily calculated based on infrared and radio studies, as well as
comparisons with the cores of other similar galaxies like M31. People
aren't significantly understimating the brightness by any means. Even
without dust in the way, 26,000 light years is a *long* way for light
to travel, and the inverse square law really takes its toll here.
Clear skies to you.

David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

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