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

A lunar eclipse that occurs when the Moon moves completely into Earth’s umbral shadow is called

Star A has an apparent visual magnitude of 13.4 and star B has an apparent visual magnitude of 15.4. Star A is ____ than star B.

Ptolemy’s model of the universe

An eclipse of the Moon (lunar eclipse) as seen from Earth, happens when

Galileo’s telescopic discovery of moons orbiting Jupiter was important because it showed that

The Moon always keeps the same side facing Earth.

The radiation emitted from a star has a maximum intensity at a wavelength of 500 nm. What is the temperature of this star?

The point in Earth’s orbit where Earth is farthest from the Sun is known as

The wavelength of the hydrogen line from level 1 to level 2 in a hot star is ____________ the wavelength of the same line in a cool star. The stars have the same radial velocities away from Earth.