I would like to view some spiral galaxy. However, I would prefer not to spend lots of $$$. What are the minimum specs a telescope must have to resolve detail in a spiral galaxy?

  • $\begingroup$ A few weeks ago I met a guy who just started with astro photography. He used a 5" apochromat for a photo of Andromeda. The image was so good you could see spiral arms. But. This was a long-time exposure with equipment that probably cost well above of 5kEUR. So. Questions: What kind of specs are you interested in? Aperture size? Or money? Or aperture size per money? What kind of observation would you like to do? Visual or photography? How far is the galaxy you want to observe? Andromeda is the next galaxy to our own one (2.54 million ly away) but other ones (e.g. M101) are much farther away. $\endgroup$ – xmjx Oct 7 '11 at 10:48
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    $\begingroup$ I just want to see a spiral galaxy through the telescope instead of looking at a picture. I would prefer to stay under 500$ US. $\endgroup$ – Dale Oct 7 '11 at 20:49
  • $\begingroup$ You'd be well served to find a local astronomy club and attend one of their star parties. Most people who attend star parties love to let newcomers take a look... $\endgroup$ – Larry OBrien Oct 8 '11 at 23:06
  • $\begingroup$ You have to look for such a galaxy in the Nice Galaxy Catalog, NGC $\endgroup$ – Georg Oct 9 '11 at 15:38
  • $\begingroup$ The Nice Galaxy Catalogs are too expensive! $\endgroup$ – Dale Oct 9 '11 at 22:28

It depends on what you mean by "view." If you just mean "see" a spiral galaxy, then you can do that without any telescope: the Andromeda Galaxy is visible naked eye from a good dark sky site. If you mean "see detail" such as spiral arms, I'd say the minimum aperture is around 10 inches (250 mm). Although you can occasionally glimpse spiral structure with smaller apertures—I've seen the spiral arms of Messier 51 in a 150-mm refractor—10 inches is the minimum to see structure in galaxies routinely.


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