Hubble finds cosmic twin of Solar System's mysterious Planet Nine Scientists find an exoplanet whose strange behavior may lead to the Solar's System hidden ninth planet. Artist's impression of Exoplanet HD 106906b Credit: ESA/Hubble, M. Kornmesser NASA's Hubble Telescope provides 14 years of data on the exoplanet HD106906 b. It exhibits strange behavior along its orbit 336 light-year away from Earth. Scientists think data from the exoplanet may explain what happened to the possibly hidden Planet Nine in our Solar System. How many planets are in our Solar System? You may think there's an obvious answer you learned in kindergarten, but the number has fluctuated between 8 and 9, depending on whether you accept Pluto as being large enough for a planet. But there's another mysterious planet that may be lurking at the edge of the Solar System – the so-called "Planet Nine". All we know about it is through inference, arrived at by judging the effects this potential planet may be having on its surroundings. Now, for the first time, scientists measured the motion of a massive exoplanet, in a different solar system, that may be exhibiting behavior similar to that of the hypothesized Planet Nine.