Long description

This diagram demonstrates the boundaries of the observable universe. The Milky Way is seen in the centre of a circle set against a black background dotted with stars. The radius of the circle is marked with an arrow labelled ‘46 billion light years’. The light that has travelled to the Milky Way is marked with a yellow arrow. The interior of this circle is labelled ‘observable universe’, with a hard border separating off the ‘unobservable universe’ outside the circle.