Nature's Densest Objects
Neutron stars are the collapsed remnants of massive stars that exploded as supernovae. With 1.4 solar masses crushed into a sphere just 20 kilometers across, they are the densest objects in the observable universe that aren't black holes. At their cores, matter is compressed beyond nuclear density — entering a regime of physics we still don't fully understand.
Extreme Surface Conditions
The surface of a neutron star is an alien landscape. Gravity is 200 billion times stronger than Earth's. Magnetic fields reach trillions of times the strength of any lab magnet. The surface temperature exceeds a million degrees. Light bends so strongly that you can see the back of the star from the front. The simulation above lets you adjust mass, radius, and spin to explore these extremes.
The Internal Structure
A neutron star has layers like an exotic onion. The outer crust is a lattice of iron nuclei in an electron sea. Deeper, nuclei become so neutron-rich they form exotic shapes called 'nuclear pasta.' The inner core may contain a superfluid of neutrons, a superconductor of protons, or even deconfined quark matter. The equation of state — which maps density to pressure — remains one of the great unsolved problems in nuclear physics.
Pulsars and Magnetars
Most neutron stars are detected as pulsars: they emit beams of radiation from their magnetic poles that sweep across Earth like a lighthouse. The fastest spin 716 times per second. Magnetars are neutron stars with magnetic fields up to 10¹¹ Tesla — strong enough to erase a credit card from halfway across the solar system and distort atomic orbitals into narrow cylinders.