NASA has revealed that China’s massive Three Gorges Dam has actually shifted Earth’s axis — and it’s subtly changing the length of our days.
Built in 2006, the dam transformed the Yangtze River into a colossal 10-trillion-gallon reservoir, generating enough electricity to power nearly six million homes every month. But that enormous volume of water also comes with planetary consequences.
According to NASA, the sheer weight of the reservoir is putting immense pressure on the Earth’s crust, redistributing mass above sea level and slightly altering the planet’s moment of inertia — the factor that determines how quickly Earth spins on its axis.
As a result, scientists estimate that Earth’s axis has shifted by about two centimeters, or nearly an inch. While that might sound insignificant, experts say such a change can have measurable effects on the planet’s rotation.
In fact, this isn’t the first time a major geological event has altered Earth’s spin. NASA previously reported that the 2004 Indian Ocean earthquake and tsunami shortened the day by a few microseconds due to the shift in tectonic plates.
Though the impact from the dam is far smaller, researchers warn that massive human-engineered structures like this highlight how even localized changes in mass can influence the delicate balance of our planet’s motion.
