单项选择题
Planetary aberration is due，in part，to（）.
A.refraction of light as it enters the Earth's atmosphere B.rotation of the Earth on it's axis C.the body's orbital motion during the time required for its light to reach Earth D.a false horizon
单项选择题 Perihelion is the point where the Sun（）.
单项选择题 Other than the Sun and Moon，the brightest object in the sky is（）.
单项选择题 Opposition occurs when（）.
