July 9, July 22, and August 5 are expected to be the shortest days of 2025 — by just a few milliseconds.
Why? Because Earth’s rotation speed isn’t constant. It changes due to:
• Shifts in Earth’s molten core
• Ocean currents and atmospheric winds
• Melting glaciers redistributing mass
• Earthquakes and tectonic activity
These tiny changes matter. Atomic clocks must stay in sync with Earth’s rotation — so scientists sometimes add or subtract a leap second to keep time aligned.
⏱️ Even a few milliseconds make a difference when measuring time with such precision!
