When astronomers realized that Pluto is not large enough to influence Neptune's orbit, the search for Planet X was resumed. The idea of Planet X was debunked in 1989, when [[Voyager 2]] flew by [[Neptune]]. NASA scientists determined that Neptune was significantly heavier than previously supposed, invalidating the earlier orbital calculations by Lowell and others. | When astronomers realized that Pluto is not large enough to influence Neptune's orbit, the search for Planet X was resumed. The idea of Planet X was debunked in 1989, when [[Voyager 2]] flew by [[Neptune]]. NASA scientists determined that Neptune was significantly heavier than previously supposed, invalidating the earlier orbital calculations by Lowell and others. |