In a 2009 interview with the Discovery Channel, Mike Brown noted that, while it is not impossible that the Sun has a distant planetary companion, such an object would have to be lying very far from the observed regions of the Solar System to have no detectable gravitational effect on the other planets. A Mars-sized object could lie undetected at 300 AU (10 times the distance of Neptune); a Jupiter-sized object at 30,000 AU. To travel 1000 AU in two years, an object would need to be moving at 2400 km/s – faster than the galactic escape velocity. At that speed, any object would be shot out of the Solar System, and then out of the Milky Way galaxy into intergalactic space.