通过测量星系的红移，科学家可以计算出它们远离地球的速度。

By measuring the ___redshifts of galaxies, scientists can calculate how fast they are moving away from Earth.

天文学家通过测量星系光谱中的红移来估算其远离我们的速度。

Astronomers estimate how fast galaxies are moving away by measuring the ___redshifts in their spectra.