Next time you’re traveling in the desert, make sure you carry plenty of water. That enticing pool of water you see far away in the distance may be a mirage, or an optical illusion.
A mirage is created when light is distorted by layers of hot air. A mirage that looks like a body of water is actually an image of the sky. Even if you don’t spend much time in the desert, you may have noticed this phenomenon when driving on the highway on a hot day. Under certain conditions you can see in the distance what appears to be a puddle of water across the road. You’ll never reach the puddle, however: it’s just an illusion. The word mirage can be used in a more general sense to refer to anything that is unattainable or a false perception.