Earth: Why, if it moves at thousands of kilometers per hour, does it not feel like we are traveling at full speed?

Photo credit, Getty Images

Article information
  • Author, Juan Francisco Alonso
  • Role, BBC News Mundo
  • 5 hours ago

Earth is the spaceship that takes us on an accelerated journey through the cosmos. The planet moves at 107,280 kilometers per hour around the Sun.

It rotates on its axis at approximately 1,666 kilometers per hour at the equator.

So why don’t we feel like we’re riding a spaceball of fire?

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Consistency and inertia

To understand this phenomenon, Chilean astrophysicist Javiera Rey gives us an example.

“Imagine you are on a plane,” says Javiera Rey, co-founder of Star Tres, an initiative aimed at spreading scientific knowledge in Latin America.

“When you take off, you feel like you’re sinking into the seat, and when you land, you feel like you’re moving forward. This is because inertia means we tend to stay in our position of rest.”

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Image caption, When a plane reaches a constant speed, it feels like it is standing still.

“When the plane reaches cruising speed, you don’t realize you’re moving, you can stop and walk.”

So when the plane stays at a constant speed, it feels like it is standing still.

The same goes for the Earth: when it moves at a constant speed, it feels like it’s not really traveling through the cosmos.

Everything on Earth, including humans, travels at this same constant speed, we rotate with the planet, so we don’t feel the movement.

But there are other key elements.

Photo credit, Getty Images

Image caption, Gravity also allows us to not feel the constant movements of the Earth.

The other force which also plays a role

Gravity also explains why we don’t feel the Earth rotating.

“Imagine getting into a Formula 1 car and moving in a straight line at a constant speed,” says Solmar Varela, a theoretical physicist and science popularizer at the Central University of Venezuela.

“At that point you won’t feel the car moving, but when you come to a corner you will feel a force pushing you towards the opposite side of the corner, as if trying to force you out of the car,” explains Mr. Varela.

“The reason you’re not thrown from the car is because you’re wearing a seat belt,” he adds.

The same goes for our planet. When it spins, it generates a centrifugal force that, in theory, should hurtle us into space.

However, Earth’s gravity is much stronger than this centrifugal force, and so we remain stuck to the planet.

“Gravity acts like the seat belt of the car,” explains Mr. Varela.

Photo credit, Getty Images

Image caption, Our inability to perceive the Earth’s movement is one of the reasons why, for centuries, it was believed that the stars revolved around our planet.

Movement is relative

The feeling that the Earth is not moving was one of the reasons why, for centuries, our planet was believed to be the center of the universe.

“For a long time, it was believed that the Earth was the center of the cosmos, because when people looked at the sky, they saw that the stars were the ones that moved,” explains Venezuelan astrophysicist Miriam Rengel, researcher at the Max Planck Institute for research on the solar system, in Germany.

“But things changed when Nicolaus Copernicus and Johannes Kepler developed the heliocentric model and Galileo discovered the four moons of Jupiter and saw that these were the planets that moved around the Sun,” adds Miriam Rengel.

Proponents of geocentrism argued that if the planet moved, we would feel it, and that if we dropped an object from a high place, it would land not at the base, but behind it.

But Galileo found a way to refute these arguments.

He experimented on a boat sailing at constant speed in a calm sea and poured a drop of water into a container.

He then noticed that, although the boat was moving forward, the drops were still falling into the container.

“He showed that everything depends on where you are,” explains Mr. Rengel.

Galileo was therefore the first to formulate the principle of relativity.

Photo credit, Getty Images

Image caption, Galileo’s studies revealed that the Earth moved and revolved around the Sun.

Accustomed and prepared

Another reason why we are not able to perceive the movement of the Earth is that we are simply used to it.

“We are used to this movement since we were born,” explains Marta Ábalos, professor of terrestrial physics at the Complutense University of Madrid.

For his part, Rey emphasizes that the hearing system of living beings has adapted to prevent the movement of the planet from making us dizzy, for example.

The fact that the atmosphere moves at roughly the same speed as the Earth also plays a role.

As the layer of air surrounding the Earth rotates at almost the same speed, we do not feel any ‘wind’ due to the Earth’s rotation,” says Ábalos.

Furthermore, according to Rey, the movement of the planet does not generate wind because “space is practically empty.”



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