prolate hypocycloid

例句：

1. 1. The shape of the planet is a prolate hypocycloid.
   行星的形状是一个扁球面体。
2. 2. The astrophysicist found that the star's orbit was a prolate hypocycloid.
   天文学家发现那颗星的轨道是一个扁球面体。
3. 3. The prolate hypocycloid is used to describe the shape of an object when it is rotated around its axis.
   扁球面体用来描述一个物体在绕其轴旋转时的形状。