[Physics] What are the minimum telescope requirements to view a nice spiral galaxy

Question

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?

Answer 1

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.