NASA's Juno probe zips around Jupiter every few weeks at speeds of up to 130,000 mph, plowing through all kinds of invisible fields in the process.
One of the strongest unseen signals the robot has encountered is Jupiter's bow shock: the point where the planet's magnetic field pushes back against a howling wind of incoming particles from the sun, creating something akin to a sonic boom.
This audio is about two hours' worth of electric field signal compressed into a few seconds, and it's eerie.
Source: NASA