Neutron stars spin 700 times per second

Neutron stars can spin 700 times per second. When a massive star collapses, its core compresses to 20 km wide but keeps its angular momentum, like a skater pulling in arms. The fastest known, PSR J1748-2446ad, rotates 716 times per second. Its surface moves at a quarter light speed. A teaspoon would weigh a billion tons. Despite this violence, pulsars are the most precise clocks in nature, rivaling atomic clocks. Astronomers use them to hunt gravitational waves. A city-sized stellar corpse, spinning faster than a blender, keeping perfect time.