File:20120831 234435.jpg

Summary
This is an image from the H-alpha sky survey. It is a composite of the Virginia Tech Spectral line Survey (VTSS) in the north and the Southern H-Alpha Sky Survey Atlas.

Licensing
The image is non-free fair use in Red astronomy.

Fair use for red astronomy
To illustrate the subject in question (an H-alpha sky survey of the Milkyway galaxy), since no picture can be obtained of the actual H-apha in natural color as it occurs in the Galaxy.

The image linked here is claimed to be used under fair use as:
 * 1) it is a scientifically significant image of the H-alpha distribution around the Milkyway galaxy from an Earth source;
 * 2) it is of much lower resolution than the original (copies made from it will be of very inferior quality),
 * 3) the photo is only being used for informational/educational purposes.
 * 4) Its inclusion in the article adds significantly to the article because it shows that H-alpha emitters exists across the Galaxy to the general public.