Gravitational torque drives multidecadal variations in length of day

Scientists have determined that gravitational torque generated deep within Earth’s inner core drives multidecadal variations in the planet’s length of day, confirming that the 24‑hour cycle is not perfectly constant. The discovery explains why measurements show the day can be slightly longer or shorter over periods of decades, a phenomenon previously observed but not understood. The peer‑reviewed study published in Nature laid out the physics of how subtle shifts in the core’s mass distribution modify Earth’s rotation speed.

It detailed the calculations linking core dynamics to observable changes in day length. Gizmodo and phys.org ran feature stories describing how the newly identified torque accounts for the planetary “glitch” that has puzzled scientists for years. The Debrief highlighted research suggesting Earth’s inner core may be secretly changing, a factor that now appears to influence day length.

Current coverage positions the gravitational‑torque model as the leading explanation for recent multidecadal day‑length shifts. Scientists will continue to monitor the torque’s magnitude through precise rotation measurements, providing data that could refine forecasts of Earth’s rotational stability. The ongoing dialogue among research journals and popular science sites signals a rapid diffusion of the concept across both academic and public audiences.