That means that its light will undergo a Doppler shift, and that can be detected.

这意味着它的光会经历多普勒频移，并且可以被探测到。

Another way is to measure the Doppler shift in a star's light due to reflexive motion as the planet orbits.

另一种方法是测量恒星光线的多普勒频移，这种频移是由行星绕轨道运行时的自反运动引起的。

If we know the planets' mass from the star's Doppler shift, we can use the planet's size to calculate its density.

如果我们通过恒星的多普勒频移知道行星的质量，我们就可以用行星的大小来计算它的密度。

The stars Slipher looked at showed unmistakable signs of a Doppler shift, the same mechanism behind that distinctive stretched-out yee-yummm sound cars make as they flash past on a racetrack.

斯莱弗发现，这些恒星明确显示出一种多普勒频移的迹象，跟赛车场上飞驰而过的汽车发出的那种连贯而又特有的“嚓——嗖”的声音属于同一机制。

While we may not see that motion directly, if we take spectra of their light, breaking it up into individual narrow colors, we can see the Doppler shift in their spectra.

虽然我们可能无法直接看到这种运动，但如果我们把它们的光谱分解成单独的窄色，我们可以看到在它们光谱中的多普勒频移。

Star forming gas clouds emit a very narrow wavelength range of radio waves, and this could be used to measure their Doppler shift, how quickly they were moving toward or away from us.

恒星形成气体云发射出波长范围非常窄的无线电波，这可以用来测量它们的多普勒频移，即它们向我们移动或远离我们的速度。

Not only that, but the amount of Doppler shift in the star is related to the mass of the planet: a more massive planet pulls harder on the star, making it move more quickly.

不仅如此，恒星的多普勒频移量还与行星的质量有关：质量更大的行星对恒星的引力更大，使恒星移动得更快。