What Is the Fastest Spinning Object in the Universe?

The Record-Breaking Millisecond Pulsar

The fastest spinning object in the universe is PSR J1748−2446ad, a neutron star that rotates 716 times per second, completing one full rotation in just 1.4 milliseconds. This extreme celestial object spins so fast that its surface moves at 24% the speed of light—over 70,000 kilometers per second.

This isn’t just any ordinary star. PSR J1748−2446ad is what astronomers call a millisecond pulsar, a type of neutron star that has been spun up to incredible speeds through a process that took millions of years to complete.

How Neutron Stars Achieve Such Extreme Speeds

Neutron stars are born from the collapse of massive stars during supernova explosions. Initially, these stellar remnants spin relatively slowly—perhaps once every few seconds. However, some neutron stars exist in binary systems with companion stars, and this is where the magic happens.

Over millions of years, the neutron star’s immense gravitational field strips material from its companion star. This stolen matter doesn’t fall directly onto the neutron star’s surface. Instead, it forms an accretion disk that spirals inward, transferring angular momentum to the neutron star and gradually spinning it up like a cosmic top.

This process, called recycling, can accelerate a neutron star from a leisurely rotation to the mind-bending speeds we observe in millisecond pulsars.

The Physics of Extreme Density

What makes this achievement even more remarkable is the sheer density of neutron stars. PSR J1748−2446ad contains more mass than our entire Sun compressed into a sphere barely 20 kilometers across—roughly the size of Manhattan. A single teaspoon of neutron star material would weigh about 6 billion tons on Earth.

This extreme density creates gravitational fields so intense that even a marshmallow dropped onto the surface would impact with the energy of a nuclear bomb. The gravitational acceleration at the surface is approximately 200 billion times stronger than Earth’s gravity.

The Limits of Spin

There are physical limits to how fast neutron stars can spin before they tear themselves apart. The current record holder operates near this theoretical maximum. If PSR J1748−2446ad were to spin just slightly faster, the centrifugal forces would overcome the star’s gravitational binding force, causing it to disintegrate.

Scientists believe the theoretical maximum spin rate for neutron stars is around 1,000-1,500 rotations per second, depending on their mass and composition. This means we may have already discovered objects spinning close to the absolute limit possible in our universe.

Discovery and Observation

Millisecond pulsars like PSR J1748−2446ad are detected through their radio emissions. As these neutron stars spin, they emit beams of radiation from their magnetic poles. When these beams sweep across Earth like a cosmic lighthouse, we detect regular pulses of radio waves with incredible precision.

The regularity of these pulses is so consistent that astronomers use millisecond pulsars as cosmic clocks, helping to test Einstein’s theories of relativity and search for gravitational waves rippling through spacetime.