The Earth spins at about 1,000 mph to the east. Why then isn’t it faster to travel west in an airplane than it is to travel east? The answer is fairly simple if you don’t overthink it.
The question itself stems from a simple misconception that, once you leave the ground, you’re no longer traveling with the rotation of the earth. In reality, the ground, the air above it, and any particles under the direct influence of the Earth’s gravity are traveling with the rotation of the planet, though the speeds differ depending on where they are.
Within the space that airplanes travel, particles (air, ground, people, planes) are still passively traveling at about 700 to 1,000 miles per hour to the east. For now, let’s think of the moving areas like the belt of a treadmill.
Overtaking The Race
When you run on a treadmill, you have to match its speed in order to stay stationary on it. Run too slowly and you get flung off the back. Run faster than the belt and you step on the front. Now, imagine that the treadmill is the Earth, both ground and sky, spinning very quickly to the east. There’s your base setup. Let’s take it to the next step.
For an airplane to zoom past hills and plains like two cars in opposite directions on a highway, the airplane would first need to be going faster than the Earth is spinning. Commercial airliners typically fly between 460 and 575 mph, which is significantly slower than the 1,000 or so miles per hour they’d have to fly to overtake the Earth’s spin. When you’re flying west, you’re still going eastward, you’re just doing so more slowly than the world around you, sending you effectively westward.
Some flights do take less time in one direction, and it does have something to do with the Earth’s rotation, just not directly. The jet stream, a fast-moving river of air in the upper atmosphere, provides a convenient tunnel for planes to travel through with an extra burst of speed. However, that boost only works if the plane is traveling in the same direction as the air. If a plane has to fly into the wind head-on, the trip will take more time. What does this have to do with the Earth’s rotation?
The jet stream is a product of the Coriolis Effect, which is a series of wind patterns and turbulence caused by the friction of fast-moving currents of air against slower moving sections. The different speeds are a result of Earth’s shape and how quickly objects move relative to the axis of rotation. Air around the poles moves more slowly than air at the equator because it’s closer to the center point of rotation. The physics of it all is a lot to take in. Fortunately, next time you’re on an airplane, all you have to worry about it sitting back and enjoying the ride.