Per Flying Magzine, the average commercial airplane has a cruising speed somewhere between 550 and 600 miles per hour. When you’re inside a plane (which is almost always painted white), you’re moving at that speed, too. And it’s because you’re in the plane, zipping along with it, that you can’t perceive how fast you’re really going.

The reason why being in a plane feels so much slower than being in a car or a train is, like the perception of a plane’s speed at a distance, a matter of reference points (rather, a lack thereof). In a car, you typically pass by all kinds of reference points, and they pass along your field of vision either quickly or not as quickly, depending on the speed you’re driving. In a plane, though, these reference points are far, far fewer.

Sara Nelson, director of NASA’s Iowa Space Grant Consortium at Iowa State University, broke down this concept in an article published on The Conversation website, where she noted, “This is the same reason why it can be hard to tell that you are driving quickly on a highway that is surrounded only by empty fields with no trees.” Nelson further said that if when inside a plane, looking out one of the plane’s round windows, you can spot the plane’s shadow on the ground, you could get a sense of the plane’s true speed.