... 轨道中线 track centre 轨道中心orbit centre 轨道周长 orbit circumference ...
双语例句
1
The orbit of the earth around the sun is eccentric because the orbit is slightly elliptical and so has effectively has two centres (neither of them the centre of the sun).
The planet and the star both orbit around a common centre of mass between them.
地球轨道的明星都围绕一个共同的质量中心之间。
3
Writing in the science journal Nature, the researchers say it's unclear how the planets, which are near the centre of the Milky Way galaxy, came to be without a star to orbit.