Patrick Weltevrede

A pulsar is a dead star spinning at breakneck speed, sending out radio pulses like a lighthouse. Usually these pulses arrive right on schedule, but occasionally there are true monsters among them — giant pulses that are thousands of times brighter than normal.

A lighthouse spins in dense fog. Its beam cuts through the gloom, but the fog itself remains invisible. That's roughly how astronomers search for dark matter: it doesn't emit light, yet it can affect the signals that reach us.