The equation uses a proportionality constant called the Hubble parameter, which says that for every million light-years of distance from us, a galaxy is moving away at an additional 21 kilometers per second.

该方程式使用一个称为哈勃参数的比例常数，它表示距离我们每百万光年的距离， 一个星系以每秒 21 公里的额外速度移动。