Expert: Paul Wagner - 3/3/2010

Question
Sir,
Images of galaxies we got are 2D or 3D?
- if 3D, how can we got it?
- if 2D, how can we distinct galaxies (spirals galaxies, elliptical galaxies...)

Answer
Hi Khanh

THe images we get of the galaxies are two-dimensional, since they are all take in the focal plane of a single telescope.  But when we see these images, we can also easily see some of the different shapes.  A spiral galaxy will look like a spiral when see face on, and will look very different when seen edge on.  But by comparing the two images, you can still see how they are the same time of galaxy.

If you look at a series of photos of soccer balls and dinner plates, you might be a bit confused at first, but after you look at them for a while, you can clearly see which one is which.

Paul Wagner