Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

In Isaac Asimov's Foundation Series, there is a planet named Terminus which is believed to be the planet farthest from the galactic center.

There are almost no visible stars in its sky, only the huge lens of the Milky Way galaxy

But what would we really see if we look at the opposite side from the galactic center (without a telescope or binoculars)? Would we see a black sky or a sky full of galaxies?

share|improve this question
3  
Such a good series... –  rfusca Jun 13 '11 at 18:51

2 Answers 2

up vote 14 down vote accepted

Asimov's description is pretty much correct. There aren't many stars out there, so the night sky away from the galactic disk would be fairly dark. Toward the galaxy you you have an edge on view of the galactic disk.

As for a sky full of galaxies, you might see a few but probably not. They are intrinsically very faint and moving a few tens of thousands of light years wouldn't do much to make them closer and therefore brighter. The sky background would be lower so you might be able to see a few more but most likely, to the unaided eye it wouldn't be much different.

So if you looked away from the galactic center, there would be a very darks sky with only a few stars and a few faint smudges just on the edge of detectability for your peripherial vision.

share|improve this answer
4  
Specifically, the Andromeda galaxy and the Magellanic Clouds. I think all the Milky Way's dwarf companions' surface brightnesses are too low to be seen with the naked eye. A globular cluster could be pretty spectacular if your Terminus happened to be close by one. Maybe it's to be assumed that there isn't, however, by the description of Terminus as being the backwater of the galaxy. –  Andrew Jun 13 '11 at 19:50
    
Thanks, dagorym and Andrew. I just thought about the List of Messier objects and I sorted it by Distance. Only Andromeda, Triangulum Galaxy and Bode's Galaxy have an apparent magnitude under 7. is there a list like that for the south sky? –  DavRob60 Jun 14 '11 at 12:41
3  
@DavRob60 A quick SIMBAD search gives three more galaxies with apparent V-band magnitude under 7: The LMC (V-mag of 0.9), the SMC (2.7), and Centaurus A (6.84) –  spencer nelson Jun 14 '11 at 19:41
1  
@DavRob60 Seds lists several southern hemisphere catalogs here: messier.seds.org/xtra/similar/catalogs.html –  Dan Neely Apr 23 '12 at 15:27

While true that you wouldn't see many galaxies with the naked eye (about as many as we can from earth), this sort of location would be an astronomer's paradise. You could study other galaxies without the interference of local stars, gas, and other impeding influences. You would be able to get a much more complete count of distant galaxies than we can from earth (for what it's worth). For the Hubble Deep-field images for example, we have to take one small pinpoint between stars that is away from the main plane of the galaxy. From your theoretical viewpoint however, we could take individual images of a much wider field of view, in practically any direction, and you would never have to worry about saturation from very bright foreground stars.

You'd still need a space telescope to make that happen of course for the extra-long exposures necessary, unless your planet just happens to be tidally locked with your star. :)

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.