Any fifth grader can tell you that the Earth is spinning. But what a fifth grader can’t probably tell you is this: if Earth is spinning to the east, and we’re in a plane flying west, shouldn’t we get to our destination faster, seeing as it’s literally spinning towards us?
Have you ever traveled from NYC to LA and wondered why the flight takes so long?
Flying west from NYC to LA takes about an hour longer than flying the return trip, but not directly because of the earth’s rotation. Instead, the earth’s rotation affects the way the wind blows on our planet.
First, when the Earth itself rotates, it’s also pulling everything on earth with it — including earth’s atmosphere and the planes in it. This includes the air in which planes fly.
While the Earth itself rotates at around 1,180 km / h to the east, the ground and everything on it are travelling even faster – at around 1,670 km / h (1,037 mph).
Even the air above the ground travels eastward at this speed. So, for an airplane to get anywhere, it has to be moving relative to the ground.
Let’s say the aeroplane’s traveling at 160 km/h (100 mph) – because it’s already moving at 1,670 km/h with the planet, plus that little bit extra, it’s able to keep itself ahead and actually get somewhere.
On the other hand, if it’s traveling towards the west, it’s actually moving 1,670 km/h MINUS 160 km/h.
Here are the major jet streams over North America:
At the equator, the Earth rotates about twice as fast as a commercial plane can fly. This rate slows down as you get closer to the poles, but still, it will always be faster than a plane.
For example, a city near the equator, like Jakarta, Indonesia, spins at around 1,000 miles per hour, while Wisconsin (at 45° latitude) spins at around 700 miles per hour.
Since it cannot match the speed of rotation of the Earth, a plane flying west technically moves to the east – just like the entire planet below. It just has engines that help it travel east a little slower than everything else, which makes it move west relative to the ground.
Still Confused? Don’t worry, MinutePhysics is here to help you: