One of life’s undeniable truths is that the Earth is constantly rotating on its axis.
What you might not know is just how fast it is doing so.
Different parts of our planet experience different rotational speeds depending on their geographical location.
The equatorial regions have the highest rotational speed, which is why rockets and satellites are often launched from there.
The speed at the equator is no less than 1,037 miles per hour.
To put this in perspective, the Shanghai Maglev train, the fastest commercial high-speed electric train in the world, travels at only one-fifth the speed of the Earth’s rotation at the equator.
Why Don’t We Feel Earth’s Rotation?
Now that you know the Earth rotates blisteringly fast on its axis, you might wonder why we don’t feel it.
The short answer is that the Earth spins at a constant speed, so there are no changes in its rotational speed.
We humans, living on the surface, move along with it at the same speed.
This is why we don’t feel any direct physical effects of the Earth’s spin.
Understanding Through the Bus Analogy
This phenomenon can be better understood with the help of a traveling bus analogy.
When you’re sitting in a bus that’s moving at a constant speed of 40 miles per hour, do you feel like you’re moving at the same speed?
Of course, you don’t because you are sitting inside it and therefore moving along with it at the same speed.
Your motion is coupled with the motion of the bus.
In technical terms, there is no relative motion between you and the bus.
We perceive motion only when there is some relative motion between two objects.
Since everything inside the bus – the seats, window bars, and other passengers – moves at the same speed as the bus, it’s somewhat difficult to imagine that all of us are clocking 40 miles per hour.
Perception of Movement and Inertia
However, when the bus makes a sharp turn, decelerates rapidly, or halts suddenly, the movement of the bus becomes obvious because, in each of those scenarios, there appears to be relative motion between the bus and you.
For instance, when the bus stops suddenly, you get pushed forward due to inertia, or when the bus turns, you sway to your side, again caused by inertia.
Applying This to Earth’s Rotation
Now let’s apply the same reasoning to the case of the Earth’s rotation.
We do not perceive the Earth’s rotation because everything that’s attached to the surface of the Earth moves at the same speed as the Earth, thereby making us, who are also attached to the surface, feel that our planet is not moving at all.
Jumping on a Moving Bus vs. Jumping on Earth
What do you think will happen if you jump inside a moving bus?
Since the bus is moving forward, will the bus floor slip beneath your feet and make you land behind the spot from where you jumped?
Of course not.
You will land in the same spot unless the bus accelerates or slows down during your jump.
Similarly, when we jump outside, our motion remains coupled with the Earth’s rotation, which is why we land in the same spot.
Given that our planet does not accelerate, decelerate, or change direction during its rotation, it’s impossible for us to physically perceive its rotation.
The Importance of Constant Rotation
As it turns out, this is also in our best interest.
For example, if the Earth were to accelerate or slow down suddenly, everything on the ground would be uprooted from its present location and thrown off, resulting in nothing short of annihilation.
Interestingly, if you managed to jump high enough – a few hundred kilometers above Earth’s surface – meaning that you decouple yourself from Earth’s rotation, you would certainly land in a different spot from where you jumped.
However, unless you’re a superhero, this probably won’t apply to your abilities.
Observing Earth’s Rotation
But that doesn’t mean we can’t observe the Earth spinning from right here on the ground.
The Sun and Moon rise in the east and set in the west because of the direction we’re rotating in.
If you set up a video camera pointed at the night sky, you’ll be able to see the stars moving.
From our frame of reference, it looks like those objects are sliding past us.
Remember, that’s just how we see it; from the Sun’s point of view, we’re all spinning in circles.