Review

#04

The effect is called ``seeing'' (or ``twinkling''). It refers to the fact that small elements of air in motion cause point sources like stars to appear as slightly fuzzy patches. Effectively, this is blurring, and so the atmosphere limits the spatial resolution (or crispness of image) for ground-based observations.

#19

You get a sense of which color bands most of the light is being radiated by an object, which is normally related to temperature. The different wavelengths can also be sensitive to different regions - stellar atmospheres, stellar winds, magnetic fields, and so on. In the example of the galaxy, our view of distant parts of the galaxy can only be measured in some wavelength bands, but not at all in others. Thus multi-wavelength approaches give us a more full view of the universe.