Yesterday, Kylie Jenner tweeted a photo full of extremely poignant questions suggesting that maybe those white trails left by airplanes aren't what they seem. But, this chemtrails conspiracy theory is definitely not new, and its origins are even weirder than you think. The basic idea is that those white trails are actually chemical formulas used by the government for a variety of reasons, possibly for controlling the weather, building a massive weapon, or simply to make us all sick. The one thing chemtrail conspiracy theorists agree on is that these chemicals are definitely not good for us. Like all good conspiracy theories, this one started off with a teensy nugget of truth. As io9 explains, in a totally speculative paper published in 1996 by the Air Force, the authors looked ahead to the year 2025 and described ways to "own the weather" in order to "remain the dominant air and space force in the future." A few years later, an article drew from that study (among other things) to popularize the "geoengineering" idea of chemtrails. And, in 2001, Representative Denis Kucinich introduced a bill that mentioned the banning of chemtrails — alongside a litany of "exotic" weapons (including extraterrestrial and mind-controlling options, of course). The bill's original language seems to come from a few UFO enthusiasts, and it never made it beyond committee. What's actually happening is the result of extremely specific atmospheric conditions. Basically, water particles are quickly condensing (hence their actual name, "contrails") and freezing around particles in airplane exhaust. The result is a type of vapor cloud that's left behind. So, it's totally understandable why one might see a bunch of contrails all at once where there's a pocket of "perfect" air, and not see any for a while after or in other parts of the sky. Proponents of the chemtrail conspiracy tend to distinguish between trails that dissipate relatively quickly (totally cool) and those that linger (probably filled with deadly toxins). Again, there is a tiny bit of truth here. NASA does distinguish between types of contrails by how long they spend in the sky and how much they spread out (affected by the humidity at the plane's altitude). All contrails contain emissions found in airplane exhaust, such as methane. But, of course, methane is released in the plane's exhaust whether you can see it or not. As Pacific Standard points out, one avenue of the chemtrail conspiracy theory leads us straight to the controversial Morgellons disease. This condition is often characterized by tiny, thread-like things supposedly growing out of your skin, and some believe that chemtrails may be a cause of Morgellons. In spite of the actual evidence against the idea (or perhaps because of it) many people still believe there's something else going on with those contrails — and that maybe it has something to do "with why Honey Bee's are Dying off really fast" as the photo on Kylie's Twitter put it. So, hey, if you're still worried, you and Kylie can join the movement.