Harvard scientists concoct a plan to figure out if Planet Nine is a primordial black hole

For many years scientists have hypothesized that there is a mysterious ninth planet in our outer solar system called Planet Nine. Scientists at Harvard University and the Black Hole Initiative have developed a new method to find black holes in the outer solar system. They want to use the system to determine the true nature of the hypothesized Planet Nine.

The recent paper highlights the ability to use the future Legacy Survey of Space and Time (LSST) mission to observe accretion flares, the presence of which could prove or disprove if Planet Nine is a black hole. The new method to search for black holes in the outer solar system developed at Harvard is based on flares that result from the disruption of intercepted comets. The study suggests the LSST can find black holes by observing for accretion flares resulting from the impact of small Oort cloud objects.

Scientists say that in the vicinity of a black hole, small bodies would approach it and melt as a result of heating from the background accretion of gas from the interstellar medium into the black hole. When the small bodies melt, they are subject to tidal disruption by the black hole, followed by the accretion from the tidally disrupted body onto the black hole. The method can detect or rule out trapped planet-mass black holes out to the edge of the Oort cloud, or about a hundred thousand astronomical units.

LSST is expected to have the sensitivity required to detect accretion flares while the currently available technology isn't able to do so. The paper focuses on learning more about Planet Nine as the first candidate for detection. Theories suggest Planet Nine is an undetected planet. However, it could also be flagged as a planet-mass black hole.