Chaotic attitude motion of a magnetic rigid spacecraft in a circular orbit of the earth is treated.
研究在地球万有引力场和磁场中的磁性刚体航天器在圆轨道上的混沌姿态运动。
The Maya also had a calendar of 35 days, based on the orbit of the earth around the sun.
玛雅也拥有35天的历,建立在地球环绕太阳的基础上。
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).
地球环绕太阳的公转轨道是偏心的,这是因为地球的公转轨道稍微呈椭圆形,所以这个轨道实际上就有两个中心(这两个中心都不与太阳的中心重合)。