Galileo challenged the idea that objects in the heavens were perfect by ________.

The velocities of seismic waves traveling from earthquake foci ________.

The light collecting area of a telescope is larger in telescopes which have a larger ____________.

The surface features of ________ are known only through satellite radar mapping.

To calculate the masses of stars in a binary system, we must measure their ________.

The largest geographic feature on the surface of planet earth is __________.

We can estimate the age of an open cluster of stars by examining _________.

The energy that is released in the hydrogen fusion reaction comes from __________.

The energy that is released in the hydrogen fusion reaction comes from __________.

The belt of constellations through which all the planets move is called the ________.

Radio telescopes measure the galaxy's distribution of _____.