为啥 “潮汐会让地球自转变慢，月球却在远离地球”？

地球与月球之间的潮汐相互作用产生摩擦力，使地球自转减速。根据角动量守恒定律，地球失去的角动量会转移给月球，使月球公转速度加快，逐渐远离地球。目前，月球正以每年约 3.8 厘米的速度远离地球，未来这种趋势还将持续，预计 10 亿年后，地球一天将延长到约 27 小时。

Why do "tides slow down the Earth's rotation, but the moon is moving away from the Earth"?

The tidal interaction between the Earth and the moon generates friction, which slows down the Earth's rotation. According to the law of conservation of angular momentum, the angular momentum lost by the Earth will be transferred to the moon, accelerating the moon's revolution and gradually moving it away from the Earth. At present, the moon is moving away from the Earth at a speed of about 3.8 centimeters per year, and this trend will continue in the future. It is expected that in 1 billion years, the Earth's day will be extended to about 27 hours.