The most common conspiracy theories surrounding the hypothetical Planet X, also known as Nibiru, are that the planet is on a collision course with Earth and that governments across the world are deliberately covering up its existence and the danger it poses to humanity. One theory claims that NASA has deliberately redacted photographic evidence of Nibiru that originally appeared on Google Sky.
Nibiru is a hypothetical, yet-undiscovered planet thought to orbit the sun in the outer reaches of the solar system. Conspiracy theorists believe that Nibiru's collision with Earth in the early 21st century will disrupt the Oort Cloud, a sphere of billions of comets loosely bound by gravity to the sun. Such a disruption, say the believers, will fling Oort Cloud comets toward Earth. Some conspiracy theorists suggest such cataclysms have happened in the past, causing mass extinctions and radical climate change. In October 2015, a viral video purporting to show Nibiru in the daytime sky over Florida triggered yet another wave of conspiracy theories.
NASA has long dismissed the theories surrounding Planet X as junk science that lacks supporting evidence. However, out of scientific curiosity, NASA has reprogrammed its interplanetary probe, New Horizons – which made history when it became the first human spacecraft to fly by the dwarf planet Pluto – to search for Planet X as it cruises out into the Kuiper Belt, a vast region of asteroids and comets outside the orbit of Neptune.