奇速英语

“天”的奥秘

The word “day” has two meanings. When we talk about the number of days in a year, we are using “day” to mean 24 hours. But when we talk about day and night, we are using “day” to mean the time between sunrise and sunset. Since the earth looks like a ball, the sun can shine on only half of it at a time. Always one half of the earth is having day and the other half night. A place is moved from day into night and from night into day over and over again by the spinning(旋转) of the earth. At the equator(赤道) day and night are of the same length. They are both twelve hours long. For six months the North Pole is tilted(倾斜) towards the sun. In those months the Northern Hemisphere gets more hours of sunlight than the Southern Hemisphere.