What spiral galaxies look like from the side

[ack]

https://twitter.com/i/web/status/1157412009899700225

 

[astrotoy]

That is a wonderful photo. The red blotches are called H II regions of ionized hydrogen (the red color is from the main electron transition from level 3 to level 2 (called H alpha) which is in the red part of the spectrum). They are markers for the spiral arms of the galaxy where star formation is occurring or recently occurred and surround very hot blue stars. So, seen in profile, the arms are closer to us. Not uncommonly, spiral galaxies are not always flat and show a tilt, which you can see on the right side of picture - the arms are slightly pointing downward, while on the left side, the arms are tilting slightly upward (draw an imaginary straight line through the galaxy and you can easily see the tilt.)

Larry