star motions的用法和樣例：
例句
- Astrometry is not the only planet-hunting method to look for a star's motion as it is orbited by a planet.
當恆星附近有一顆行星的時候天體測量並不是唯一的一種通過觀察恆星運動搜尋行星的辦法。 - But the earth is in motion relative to the sun, the sun is in motion relative to some other star, and so on.
但地球相對於太陽運動，太陽相對於某些其他恆星運動，等等。
