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> I can see many galaxies from where I stand. If half a dozen is "many", then sure. But you probably live far from any cities then. http://en.wikipedia.org/wi

> I can see many galaxies from where I stand. If half a dozen is "many", then sure. But you probably live far from any cities then. http://en.wikipedia.org/wiki/List_of_galaxies#Naked-eye_galaxies http://en.wikipedia.org/wiki/List_of_galaxies#Naked-eye_gala... (The list includes objects that are very difficult to see, and some only "reportedly" seen naked-eye.) > They would appear even brighter without a local galaxy to wash them out. There's no reduction in contrast in the direction perpendicular to the galactic plane. And yet the naked eye doesn't perceive the sky there "totally covered in fuzzy dots". The naked eye has a lot of trouble seeing anything beyond the Local Group - and these are a handful of close-knit galaxies. You need telescopes for that, with plenty of aperture. Once the aperture is comparable to the diameter of your car's wheels, or bigger, then yes, you get the "my god, it's full of galaxies" effect.

JoeAltmaier 12y ago
I'm an idiot. I confused nebulae etc for galaxies. Not an astronomer. So most of what we see are constructions inside our own galaxy? I see what you mean - the sky would be a very lonely place for the intergalactic skygazer.
- Florin_Andrei 12y ago
  No problem, it's a pretty common mistake. Every single star you can see with your naked eye is inside our galaxy. Even with telescopes - you'll need a very big telescope, by amateur standards, to resolve stars in other galaxies. As for non-stellar objects: Naked-eye galaxies are very few - they're all on that short list linked above. And only the first half are easily visible, and then half of those are in the southern hemisphere. Omega Centauri actually almost looks like a fuzzy star - almost. It's pretty small. You can see some nebulae (like the Great Orion Nebula) and star clusters (like M13) naked-eye, but they are only a few, and you'd have to drive far into the middle of the desert for most if not all.
  - tjradcliffe 12y ago
    This is the thing that strikes me as immediately weird about this result: as you point out, we can resolve stars in other galaxies. We've been able to for a long time. So why hasn't anyone ever noticed this extra-galactic population? They'd show up as anomalous field stars, probably with odd proper motions. If you think of it in terms of the Local Group, every galaxy should have a "halo" of these free stars around it in a radius comparable to half the distance between galaxies. Admittedly that's pretty low density, but is it really low enough that no one has ever seen one of these objects? Or are they only present at very high redshift (and if so, what happened to them?)
    - JoeAltmaier 12y ago
      Are there discernible proper motion to extra-galactic objects? Our seasonal excursion of 186 million miles around the Sun looks pretty tiny in comparison.
      - Florin_Andrei 12y ago
        The parallax can only be used for things inside this galaxy (and until very recently, only in our immediate vicinity within). It's the very first step outside the solar system in the cosmic distance ladder. Other methods must be used outside the galaxy. http://en.wikipedia.org/wiki/Cosmic_distance_ladder http://en.wikipedia.org/wiki/Cosmic_distance_ladder
    - Florin_Andrei 12y ago
      I guess two reasons: - the population density of extra-galactic stars is super low - outside our galaxy we're only discerning a fraction of the biggest nearest stars anyway You're looking for the odd ball at the remote end of a huge concert hall packed with regular balls.

JoeAltmaier 12y ago

I'm an idiot. I confused nebulae etc for galaxies. Not an astronomer. So most of what we see are constructions inside our own galaxy? I see what you mean - the sky would be a very lonely place for the intergalactic skygazer.

Florin_Andrei 12y ago
No problem, it's a pretty common mistake. Every single star you can see with your naked eye is inside our galaxy. Even with telescopes - you'll need a very big telescope, by amateur standards, to resolve stars in other galaxies. As for non-stellar objects: Naked-eye galaxies are very few - they're all on that short list linked above. And only the first half are easily visible, and then half of those are in the southern hemisphere. Omega Centauri actually almost looks like a fuzzy star - almost. It's pretty small. You can see some nebulae (like the Great Orion Nebula) and star clusters (like M13) naked-eye, but they are only a few, and you'd have to drive far into the middle of the desert for most if not all.
- tjradcliffe 12y ago
  This is the thing that strikes me as immediately weird about this result: as you point out, we can resolve stars in other galaxies. We've been able to for a long time. So why hasn't anyone ever noticed this extra-galactic population? They'd show up as anomalous field stars, probably with odd proper motions. If you think of it in terms of the Local Group, every galaxy should have a "halo" of these free stars around it in a radius comparable to half the distance between galaxies. Admittedly that's pretty low density, but is it really low enough that no one has ever seen one of these objects? Or are they only present at very high redshift (and if so, what happened to them?)
  - JoeAltmaier 12y ago
    Are there discernible proper motion to extra-galactic objects? Our seasonal excursion of 186 million miles around the Sun looks pretty tiny in comparison.
    - Florin_Andrei 12y ago
      The parallax can only be used for things inside this galaxy (and until very recently, only in our immediate vicinity within). It's the very first step outside the solar system in the cosmic distance ladder. Other methods must be used outside the galaxy. http://en.wikipedia.org/wiki/Cosmic_distance_ladder http://en.wikipedia.org/wiki/Cosmic_distance_ladder
  - Florin_Andrei 12y ago
    I guess two reasons: - the population density of extra-galactic stars is super low - outside our galaxy we're only discerning a fraction of the biggest nearest stars anyway You're looking for the odd ball at the remote end of a huge concert hall packed with regular balls.