Mars and Earth have orbits which change with time.

火星和地球的轨道随着时间而改变。

The planet is probably in orbit around a small star.

这颗行星很有可能环绕一颗小行星运行。

the radius of the orbit of the planet Jupiter round the sun.

木星绕太阳运行的轨道半径。

In 1957 the Soviet Union launched the first satellite to orbit the earth.

1957年，苏联发射了第一颗绕地卫星。

About 120 planets have been discovered orbiting other stars.

已发现约有120颗行星环绕其他星体的轨道运行。 。