It may look empty to human eyes but there’s actually a lot going on in “empty space”. Aside from physical objects that are just too small to detect from Earth (

It may look empty to human eyes but there’s actually a lot going on in “empty space”. Aside from physical objects that are just too small to detect from Earth (small asteroids (some gravitationally bound to the sun, others just passing through), dust, fragments of ancient collisions, gas, isolated molecules, and hydrogen and helium leftover from the formation of the solar system), there is also the ever-blowing solar wind - particles from the sun heading outwards - and a hailstorm of photons emitted from far off sources (other stars and galaxies, nebulae, pulsars, the extreme red-shifted radiation of distant energetic events… and much much more), passing through allowing us to see the rest of the universe. On top of these natural sources of EM radiation, our solar system at least tingles with human-created radio waves. Empty space also vibrates with gravitational waves, which we are only just starting to be able to detect. We theorise that any remaining emptiness might actually be boiling over with the continual creation and destruction of virtual particles. And who knows what’s going on with dark matter?