Imagine the Sun crammed into a city. That's not fiction.
Imagine the Sun's entire mass squeezed into a ball roughly 20 kilometres across — about the width of a city. That is a neutron star, and it is one of the most extreme objects the universe produces. When a massive star exhausts its fuel, it collapses in a supernova, and what remains is this tiny, impossibly dense remnant. How dense? A single teaspoon of its material would weigh around a billion tonnes on Earth. The surface gravity runs billions of times stronger than what keeps your feet on the ground. Some of these stars spin hundreds of times every second, sweeping beams of radiation across the cosmos — we call those pulsars, and they clock in like the universe's own metronomes. Follow Deep Field Vault for more of the universe's strangest truths.