Does Our Solar System Contain a Primordial Black Hole?

there in the dark. But as the search for Planet nine wears on and astronomers have yet to so much as get a glimpse of it, some researchers are pondering what else the object could be. Might it not be a planet at all? Could it be a primordial black hole? The Solar System is a big place, and while our astronomical techniques are rapidly advancing, many tiny bodies in the

outer Solar System have yet to be found. Planet nine is thought to be a rather more substantial object, however, with a massive around five to ten Earth masses scooting around the Sun at an average distance of four to eight hundred astronomical units or a US, since one AU is the average distance at which Earth orbits the Sun. That's ten to twenty times the orbital distance at which Pluto orbits the Sun, So if it exists, planet nine takes between ten thousand and twenty thousand years to complete

just one orbit. The possibility of a large world orbiting the Sun at such a huge distance is captivating. Studies of other star systems reveal that exoplanets between the masses of Earth and Neptune are relatively common. Why our Solar System doesn't contain a world with this mass range is

a puzzle. But if Planet nine really is out there, it would be a profound historic discovery that would reshape our understanding of the system of planets that orbit our Sun. Suffice to say, any planet with an orbit this extreme would be very difficult to spot, but astronomers are scouring infrared surveys with hopes of seeing a distant object slowly

crawl across the sky. If it's out there, planet nine should be emitting infrared radiation entered leaking from the planet since its formation, but so far, apart from the gravitational effects of something in the outer Solar System, there's precious little direct evidence for Planet nine existence. Enter the black

hole hypothesis. In September of twenty nineteen, astronomer's Jacob Schultz of Durham University and James Unwin of the University of Illinois Chicago published a new study describing their alternative hypothesis that the gravitational weirdness in the outermost reaches of the Solar System isn't being caused by a planet at all. Instead, they pointed to the potential presence of a primordial black hole, a theory that's caused a bit of a stir No.

This kind of black hole does not pose a danger to the rest of the Solar System, it would be too small for that, but in the distant regions of our Solar System its impact would be significant. The only evidence we have for Planet nine existence are the gravitational effects it's having on trans neptune objects, and black holes are the most gravitationally endowed objects in the universe. After all, Primal real black holes are the most ancient kind of

black hole. They're hypothesized to have formed right after the Big Bang. Density fluctuations in the early universe would have rapidly formed black holes of all masses. These ancient objects would have been flung throughout the cosmos, and over time they would have slowly evaporated via Hawking radiation, smaller ones popping out of existence first. But let's back up a step. Why designed to think that some extreme object is out there?

In planet Hunter's Constantine, Batiguon and Mike Brown of Caltech announced their discovery of a group of very distant trans Neptunian objects that were all strangely clustered and moving with similar orbital alignments. Their orbital alignment was also weirdly tilted, so it appeared they were all being corralled by gravitational

interactions with a larger planetary body. But no other large planetary body exists in that region, So Batigan and Brown hypothesized than an as get to be discovered planet was out there, and so the hunt began. While many theories of cosmic evolutions suggest that primordial black holes should exist, we have yet to directly observe one, though there is

some compelling indirect evidence. Take, for example, micro lensing events, the transient brightening of stars caused by a massive object passing in front of them, causing a brief brightening via the curvature of space time, creating a sort of magnifying lens. Analysis of these micro lensing events suggests that there's a population of small black holes out there with no other visible clues except for their gravitational impact on space time.

Schultzon Unwin took a fresh look at the trans Neptune object peculiarities and simulated what would happen if a black hole with a mass of between five and ten Earth masses had an extreme orbit around the Sun. Sure Enough, their models suggest that a primordial black hole with a mass within this range would cause orbital perturbances like the ones already observed in the population of trans Neptune objects. This could also explain why little optical or infrared observational

evidence for planet nine exists. A primordial black hole would generate neither signal. In fact, if a black hole is nearby, it may also be dragging around a cloud of dark matter that could be generating different types of radiation. The researchers therefore suggest, based on their findings, that the experimental program needs to be expanded, including searches for high energy cosmic rays like X rays and gamma rays coming from

moving sources. While this is an interesting avenue of study, replacing a hypothetical planet with a hypothetical type of black hole, maybe over complicating the mystery of planet nine. We spoke with Mike Brown. He said, could a black hole explain the gravitational effects we are seeing in the outer Solar System? Absolutely? All we know is that there is a six earth mass something out there, and we don't know what the

something is. Brown points out that a planet would be the most obvious something, but as long as it has a mass of a few earths, it could be anything. But the plausibility of it being an anything other than a planet is extremely low, to say the least. With tongue in cheek, Brown added, it might be a six earth mass hamburger or a burrito, but yes, it might also be a six earth mass black hole. The physics, of course, don't care one bit what the six earth

masses are made of. You could equally well hypothesize that every exoplanet that we only detect via the radial velocity method is a black hole. Is it possible? Yes? Does it make any sense in the universe? No. While investigating other gravitational sources of what may be messing with transniptune objects is good science, it's more likely the planet nine

is a planet and not a primordial black hole. Astronomers just have to keep searching, and there's a growing consensus that it will be discovered in the not so distant future. We'll keep you updated. Today's episode was written by Dr Ian O'Neill and produced by Tyler Klang. Brain Stuff is production of I Heart Radio's How Stuff Works. For more on this and lots of other topics that are surprisingly dense for their size, visit our home planet, how stuff

Works dot com. And for more podcasts from my heart Radio, visit the heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.