Each GPS satellite zips along at about 14,000 kilometers per hour, meaning that its onboard atomic clock lags the pace of clocks on the earth by about seven microseconds per day, Will calculates.

• 威尔计算了一下，每个GPS卫星每小时约飞行1万4000公里，这表示它上头的原子钟比地上的每天要慢上约7微秒。