A Teaspoon of Neutron Star Would Weigh About a Billion Tons
A dead star packs up to twice the mass of the Sun into a ball the size of a city. A sugar cube of its material would weigh as much as a mountain.
Key points
- A sugar cube of neutron star material would weigh about 1 trillion kilograms on Earth.
- NASA puts the number that plainly, and it is not a rounding trick.
- A neutron star starts as a star much bigger than the Sun.
A sugar cube of neutron star material would weigh about 1 trillion kilograms on Earth. That is about a billion tons, roughly the weight of a mountain, held in a lump that fits on a teaspoon.
NASA puts the number that plainly, and it is not a rounding trick. A neutron star is the densest material scientists can directly observe anywhere in the universe.
What a neutron star is
A neutron star starts as a star much bigger than the Sun. When a star between about 7 and 19 times the mass of the Sun runs out of fuel, its core collapses and the outer layers blow off in a supernova explosion. What is left is the crushed core.
Gravity squeezes that core so hard that protons and electrons are forced together into neutrons. The collapse stops only when the matter can be squeezed no further. The result is a sphere about the size of a city, around 20 kilometres across, holding up to twice the mass of the Sun.
Why a teaspoon weighs so much
Ordinary matter is mostly empty space. An atom is a tiny nucleus with electrons orbiting far away, by atomic scale. Neutron star matter has had that empty space crushed out of it. Pack the mass of a star into a city sized ball and every small piece of it carries an enormous share of that mass.
Science News Explores, the youth edition of Science News, makes the same point with a pyramid comparison: one teaspoon of neutron star material, at about a billion tons, matches roughly 166 Great Pyramids of Giza. Different spoon, same impossible weight.
Spinning faster than a kitchen blender
The collapse does one more strange thing. Just as a spinning skater speeds up when she pulls her arms in, a collapsing star spins faster as it shrinks. Some neutron stars, called pulsars, send out beams of light that sweep past Earth as flashes each time they turn.
The fastest known pulsar, PSR J1748-2446ad, spins 43,000 times every minute. NASA notes that is about twice as fast as a typical household blender. And pulsars keep time so steadily over long stretches that astronomers compare them to atomic clocks.
The honest limit of the comparison
No one will ever lift that teaspoon. The material only stays that dense under the crushing gravity of the star itself, and the surface gravity of a neutron star would destroy anything that came close. The teaspoon is a thought experiment, a way to make a number the human mind can hold.
But the number is real. Somewhere in space sit the remains of dead stars, each one a city sized ball heavier than the Sun, spinning in the dark. A spoonful of one would outweigh a mountain. That is how much matter gravity can force into almost no space at all.