nucleus

This makes neutron stars like giant atomic nuclei the size of a city, but holding the mass of our Sun.

Protons and neutrons, the particles making up the nuclei of atoms, are made up of smaller particles called quarks.

These jets are found in active galactic nuclei known as quasars, and they're created as dust and gases rapidly fall into the feeding black hole.

As the sun sets, your eyes send signals about the dwindling light to a part of your brain called suprachiasmatic nucleus.

When sunlight reaches our eyes, light sensitive cells in the retina send a signal that travel along the optic nerve to our suprachiasmatic nucleus.