by Sid Perkins, Science Magazine
For nearly 5 years, growing numbers of scientists have blamed the weird orbits of distant solar system objects on the gravitational effects of an as-yet-undiscovered “Planet Nine” that lies in the icy realm far beyond Neptune. But a pair of physicists is now floating an intriguing idea that could offer a new way to search for the object: What if that supposed planet is actually a small black hole?
Previous studies have suggested Planet Nine, which some astronomers refer to as “Planet X,” has a mass between five and 15 times that of Earth and lies between 45 billion and 150 billion kilometers from the sun. At such a distance, an object would receive very little light from the sun, making it hard to see with telescopes.
To detect objects of that mass, whether planets or black holes, astronomers can look for weird blobs of light formed when light “bends” around the object’s gravitational field on its journey through the galaxy (simulated image above). Those anomalies would come and go as objects move in front of a distant star and continue in their orbit.