听了爷爷的几次讲解,亮亮感到地球的奥妙还真不少。这不,星期天一到,他和表妹甜甜又去找爷爷。亮亮:“爷爷,地球环绕太阳公转是个椭圆形的轨道吧?”甜甜:“姥爷,地球自转有个自转轴吧?”爷爷:“对。你们谁说说白天和黑夜是怎么回事?”亮亮:“地球自转时,朝向太阳的半球是白天, After listening to my grandfather several times to explain the mystery of the earth a lot of really bright. No, it was Sunday and he and his cousin were sweet looking for grandpa again. Bright: “Grandpa, the Earth orbiting the sun is an orbital orbit?” Sweet: “Grandpa, there is a rotation axis of Earth rotation, right?” Grandpa: “Yes, who are you talking about day and night, what happened? ”Bright:" When the Earth rotates, the hemisphere toward the sun is daylight,