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Our galaxy from the Sag. dwarf



 
 
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  #1  
Old December 16th 04, 05:32 PM
John den Haan
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Default Our galaxy from the Sag. dwarf

Hello,

Sometimes I wonder what our galaxy would look like from a vantage point
inside the Sagittarius dwarf. Wouldn't it be an absolutely splendid sight to
be able to look at a major galaxy from such 'little' distance? Just like
'we' worshipped the sun and the moon in ancient times, our galaxy must be
(or must have been) worshipped by any inhabitants of the dwarf After all,
it has to be a very prominent part of their night sky. Imagine what you'd
see with a telescope...

--
Clear skies to you!

John den Haan (johnDOThaanATchelloDOTnl)
Mercurius public observatory
Dordrecht, Netherlands
http://www.sterrenwacht.dordt.nl


  #2  
Old December 17th 04, 08:02 AM
Odysseus
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CeeBee wrote:

"John den Haan" wrote in alt.astronomy:

Sometimes I wonder what our galaxy would look like from a vantage
point inside the Sagittarius dwarf. Wouldn't it be an absolutely
splendid sight to be able to look at a major galaxy from such 'little'
distance?


Not really. We do the same with the majority of our own galaxy at far
lesser distance, and each clear night you can see the result. Be it from
the sun or from a nearby galaxy, the overall brightness would still be the
same, and in the case you meantion the distance would make it even less
bright.

But even so, the difference in perspective would be illuminating, so
to speak. From here in the plane we see the Galaxy as a fairly
uniform band, and its central regions are mostly obscured. For me at
least, being able to see the hub and some of the spiral structure,
even if only faintly, would be very satisfying.

--
Odysseus
  #3  
Old December 19th 04, 02:32 PM
Benoît Morrissette
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On 17 Dec 2004 16:39:20 GMT, CeeBee wrote:

Odysseus wrote in alt.astronomy:


But even so, the difference in perspective would be illuminating, so
to speak. From here in the plane we see the Galaxy as a fairly
uniform band, and its central regions are mostly obscured. For me at
least, being able to see the hub and some of the spiral structure,
even if only faintly, would be very satisfying.


With a telescope, certainly, but not with the naked eye.

The OP's idea assumes that the brightness of the Milky Way would increase
with distance, as you would it see even more clearly than from a shorter
distance. But the luminosity stays the same, and at say twice the distance
the brightness is already four times smaller.

A good example is M31. It's very large, under dark skies visible with the
naked eye, yet you're not able to see any details or structure with the
naked eye.


If i'm not mistaken, M31 is 3 degrees wide: 6 times the diameter of the full
Moon!

In his 1951 book "Foundation", Isaac Asimov place the planet "Terminus" on the
far edge of the Galaxy. He write: "The Galaxy was shining very high in the sky,
stretching its huge oval from horizon-to-horizon. Compared to it, the few stars
that remained in these confines of the universe looked like small candles."
(translated from the french version)

That should be a magnificient sight!!

M33 is another example. Bigger diameter than the full moon, yet
extremely difficult to spot.

I think we're spoiled with those impressive atronomical pictures, and
sometimes assume that galaxies are intense sources of bright light. The
reality of our own vision of the milky way with our naked eyes, stunning
nevertheless, shows almost the opposite.


  #4  
Old December 19th 04, 03:29 PM
Jonathan Silverlight
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In message , Benoît
Morrissette writes
On 17 Dec 2004 16:39:20 GMT, CeeBee wrote:

Odysseus wrote in alt.astronomy:


But even so, the difference in perspective would be illuminating, so
to speak. From here in the plane we see the Galaxy as a fairly
uniform band, and its central regions are mostly obscured. For me at
least, being able to see the hub and some of the spiral structure,
even if only faintly, would be very satisfying.


With a telescope, certainly, but not with the naked eye.

The OP's idea assumes that the brightness of the Milky Way would increase
with distance, as you would it see even more clearly than from a shorter
distance. But the luminosity stays the same, and at say twice the distance
the brightness is already four times smaller.

A good example is M31. It's very large, under dark skies visible with the
naked eye, yet you're not able to see any details or structure with the
naked eye.


If i'm not mistaken, M31 is 3 degrees wide: 6 times the diameter of the full
Moon!

In his 1951 book "Foundation", Isaac Asimov place the planet "Terminus" on the
far edge of the Galaxy. He write: "The Galaxy was shining very high in
the sky,
stretching its huge oval from horizon-to-horizon. Compared to it, the
few stars
that remained in these confines of the universe looked like small candles."
(translated from the french version)

That should be a magnificient sight!!


Why? It isn't going to be any brighter than the Milky Way as we see it;
in fact it's going to be fainter, because you're further from the star
clouds nearer the centre of the galaxy, and if you're far enough from
the plane of the galaxy to see the elliptical shape it will be even more
spread out. The Milky Way is only prominent because we are looking
through a narrow sheet of stars.
It is _not_ going to look like photos, or that scene at the end of "The
Empire Strikes Back".
--
What have they got to hide? Release the ESA Beagle 2 report.
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