Today, Astronomers Can Measure Distances Directly to Worlds Like Venus

Multiple Choice

Today, astronomers can measure distances directly to worlds like Venus, Mars, the Moon, or the satellites of Jupiter by

A) bouncing radar beams off them
B) using x-ray telescopes
C) using the Hubble Space Telescope to triangulate with
D) using Cepheid variable stars that lie behind the planets
E) sending graduate students out with very long tape measures