Is the Milky Way Really a Spiral Galaxy?

[pixel01]

Hi all,

People all say that the Milky Way is a spiral galaxy. But we are inside it, how can astronomers know that it is spiral but not irregular or elliptical .

Thanks

 

[FunkyDwarf]

I think because you can use different techniques to view different distances through the dust and gas in the plane and so build up a picture through a series of verticle slices perpendicular to the plane, though I am not sure. Good question.

 

[russ_watters]

We know it certainly could not be irregular or elliptical based on the ditribution of stars visible to the naked eye in the swath of the Milky Way. The fact that the Milky Way visible to us is a narrow swath of stars and not an irregular jumble implies a spiral galaxy.