To measure how Mercury spins, astronomers sent ________ to Mercury and used theDoppler shift to determine how fast it was rotating.
A)probes
B)laser beams
C)radar beams
D)a satellite
E)a single frequency radio signal

Question

Quizplus · Accepted Answer

Astronomers used radar beams to measure how Mercury spins. By bouncing radar beams off the planet and analyzing the Doppler shift in the reflected signals, they were able to determine Mercury's rotation rate.

To Measure How Mercury Spins, Astronomers Sent ________ to Mercury