The Universe is filled with invisible mass, dark matter, which reveals itself only through gravity. One hypothesis suggests that dark matter consists of primordial black holes — objects formed in the extreme conditions just after the Big Bang. These black holes could have the mass of an asteroid and be smaller than an atomic nucleus. Because of their tiny size and weak interaction, they can pass straight through planets without leaving a trace. Stephen Hawking showed back in the 1970s that such holes should emit radiation (known as Hawking radiation) and eventually explode, yet their existence has never been confirmed experimentally.

Now astronomers have devised strategies to track down these elusive objects. The first method uses pulsars — rapidly spinning neutron stars that emit radio pulses with the regularity of a cosmic lighthouse. If a primordial black hole flies near such a pulsar, its gravitational field will perturb the pulse period, causing a characteristic glitch in the rhythm. This gravitational disturbance could be picked up by a network of gravitational wave detectors — ripples in spacetime predicted by general relativity. The second method relies on a black hole colliding with an icy body beyond Neptune's orbit. On impact, kinetic energy turns into heat, the gas becomes incandescent, and for a fraction of a second it flares brighter than a full Moon, like a signal fire visible from vast distances.

These approaches open up the possibility of detecting dark matter directly within the Solar System, turning it from a hypothetical invisible entity into a target for observational astronomy.