The speed of light.
Wavelength and frequency.
Graphs of intensity vs. wavelength.
How light is made from random motions.
Light is made of photons.
How light is made from ordered motion of electrons in atoms and molecules.
Measuring the spectrum of light from the Sun tells us what the Sun is made of.
The wavelength of light emitted from a moving object is shifted.
The apparent brightness of an astronomical object depends on its distance from us.
Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA firstname.lastname@example.org