After decades of theories and attempts to solve the mystery of Death Valley's sailing stones, a trio of scientists has finally caught the process on tape. Their study started years ago, when two of them (a biologist and an engineer) hauled 15 GPS-equipped rocks onto Racetrack Playa, the dry lake where the famous stones are found. It wasn't until 2013, when a planetary scientist made their two-man band a trio, that they hit the jackpot, though. Apparently, it takes a precise combination of water, ice and wind for the rocks to move. First, the water that floods the lake (which happens rarely) should be around three inches deep, so when it freezes, it forms thin, windowpane-like ice sheets beneath the rocks. Then, it should be sunny the day after that in order for the ice to crack, and for 10MPH winds to propel the rocks forward.
The stones the group caught on cam moved only a few inches per second, but some remained in motion for as long as 16 minutes and most sailed on the wet ground several times, so they traveled as far as 200 feet. Death Valley's sailing stones almost always make it to various lists of nature's mysteries, and we wouldn't even be surprised if there are people who truly believe they're moved by ghosts or aliens. If you need to see it happen to believe those findings, make sure to the watch time-lapse video below and read the team's paper published in PLOS One.