I want to examine the surface of a planet that is completely covered by a thick layer of clouds all the time. What wavelength of electromagnetic radiation would I be smartest to use?

A. visible light

B. x-rays

C. radar waves

D. ultra-violet

E. none would work

Answer:C

Explanation:

Radar waves will be useful to examine the surface of the planet.

Radio waves are the shorter wavelength microwaves ranging approximately 1 cm.

Short wavelength causes large reflection from large objects. These waves are useful to detect smaller objects like water drops in the cloud.

They can penetrate clouds and that is why they are used in weather forecasting, air traffic control, etc.