Why do sunspots appear dark in pictures of the Sun?
1. They actually are fairly bright but appear dark against the even brighter background of the surrounding Sun.
2. They are tiny black holes, absorbing all light that hits them.
3. They are holes in the solar surface through which we can see to deeper, darker layers of the Sun.
4. They emit light in other wavelengths that we can't see.
5. They are too cold to emit any visible light.