A 'primordial' black hole may zoom through our solar system every decade

If microscopic black holes born a fraction of a second after the Big Bang exist, as some researchers suspect, then at least one may fly through the solar system per decade, generating tiny gravitational distortions that scientists can detect, a new study finds.

These findings suggest that if astronomers can discover and confirm the existence of such gravitational disruptions, they may be able to solve the mystery behind the nature of dark matter, the unseen material that many researchers suspect makes up about five-sixths of all matter in the cosmos.

Many researchers suggest that dark matter may be composed of unknown particles, but no experiment to date has discovered new particles that might be dark matter. As such, one alternative that scientists are exploring to explain dark matter are so-called primordial black holes, ones that have existed since the dawn of time.

Previous research suggests that about 86% of matter in the universe is composed of an essentially invisible substance called dark matter. Scientists infer dark matter's existence from its gravitational effects on everyday matter and light, but it currently remains uncertain what it might be made of.

Black holes get their name from their immense gravitational pulls, which are so powerful that not even light can escape. If a black hole does not give away its existence — for instance, by ripping apart a star — it may remain undetected against the black of space.

Over the decades, astronomers have detected many black holes, from stellar-mass black holes typically about five to 10 times the sun's mass to supermassive black holes millions to billions of solar masses in size. In contrast, the new study examined primordial black holes, which previous research suggests may only be about the mass of a typical asteroid — that is, about 110 billion to 110 million billion tons (100 billion to 100 million billion metric tons).

"The black holes we consider in our work are at least 10 billion times lighter than the sun, and are barely larger in size than a hydrogen atom," study co-author Sarah Geller, a theoretical physicist at the University of California at Santa Cruz, told Space.com.