Mars' Rotation Speeds Up, Shortening Days

Mars is spinning faster each year, shortening its days by a fraction of a millisecond.
Data from NASA's InSight lander precisely tracked Mars' accelerating rotation.
The reason for Mars' accelerating spin is still unknown, but theories include polar ice shifts.
InSight's measurements also refined estimates of Mars' core size and density.
The findings provide insights into Mars' interior structure and evolution.