An absorption spectrum is also called a bright-line spectrum.

The total amount of illumination changes during the lunar cycle of phases.

You are standing near a railroad track and a train is moving toward you at 60 mph and blowing its horn. What will you notice as the train moves past you?

In the Northern Hemisphere, the sunlight moves from right to left across the surface of the Moon during the waxing phases.

Earth’s atmosphere is fully transparent only to visible and radio light.

An observer at Earth’s geographic north pole would find _______

All the constellations in the sky were created by the Greeks.

Cosmic rays are electromagnetic radiation.

Newton concluded that a force from the Earth had to act on the Moon because

Ancient astronomers thought the heavens were perfect circles, spheres, and unblemished.