开普勒- 9的这颗小行星绕其恒星公转一周仅需要一天半，它的轨道距恒星仅有250万英里。
The small Kepler-9 planet completes an orbit in just over a day and a half at a distance of 2.5 million miles from the star.
开普勒- 9的这颗小行星绕其恒星公转一周仅需要一天半，它的轨道距恒星仅有250万英里。
The small Kepler-9 planet completes an orbit in just over a day and a half at a distance of 2.5 million miles from the star.
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