File this one away for bar trivia night: The planet closest to Earth is not Venus. So say researchers in a paper in Physics Today touting the new mathematical method they devised that spit out the true nearest neighbor when distance is averaged over time: Mercury. And here's the weirder finding: Mercury is also the closest neighbor, on average, to the rest of the planets in our solar system. While it's true that when Earth and Venus make their closest approach, Venus is indeed closer to Earth than any other planet will get, it's also true that Venus is just as frequently on the opposite side of the Sun as Earth—much farther away from us than Mercury ever gets.
Just averaging those two distances to get 1.0 astronomical units (AU), as has been done, isn't precise enough, the researchers argue. The explanation of their "point-circle method" is super technical, but Gizmodo explains that essentially, their models look at the distance "between every point along one planet’s orbit and every point along the other planet's orbit." The upshot: Venus' average distance from Earth is 1.14 AU and Mercury's is 1.04 AU. Futurism explains that Mercury's nearness to the Sun is the key: Because of it, its nearest and farthest distances from Earth don't vary that much, and that holds true for all the planets. (Read more Venus stories.)