Neutron star

A star the size of a city

The center left in the middle of the explosion is a neutron star. It is about 1.4 times heavier than the Sun, yet only about 24 km across, about the size of a big city. One teaspoon of it would weigh about 1.9 billion tonnes. It is the densest kind of star in the universe.

Why?When the center collapses, it is squeezed so hard that all the empty space inside its atoms disappears. Electrons are pushed into the atomic nuclei, and almost the whole star is left as particles called neutrons.

Learn moreGravity at the surface of a neutron star is about 130 billion times stronger than on Earth (worked out from average values). The gas scattered by the explosion glows as a cloud for thousands of years. This is called a supernova remnant.

When

About 12 million years old

Star we are watching

Neutron star

Size · state

About 24 km across · 1.4 times the Sun’s mass