SETI searches concentrate on the "waterhole" in the electromagnetic spectrum. This is the range of wavelengths:
A) 18 to 21 meters
B) 18 to 21 centimeters
C) 18 to 21 millimeters
D) 18 to 21 nanometers

Question

Quizplus · Accepted Answer

The "waterhole" in the electromagnetic spectrum, where SETI searches concentrate, is the range of wavelengths from 18 to 21 centimeters. This range is chosen because it is relatively quiet in terms of natural cosmic noise and falls within the microwave region, where hydrogen (at 21 cm) and hydroxyl (at 18 cm) emissions occur, which are fundamental to water.

SETI Searches Concentrate on the "Waterhole" in the Electromagnetic Spectrum