Why Earth spinning is not felt?

Reason for not feeling the Earth spinning

Earth makes one rotation every 24 hours and orbits the sun at around 67,000 mph (110,000 km/h). So why can't we feel that? When you're going around and around on a carnival ride, you feel it, you're pulled outward, and all you can do is hang on. Our planet is rotating much faster than that, so why aren't we all holding on for dear life? Why can't we feel Earth's rotation? Right now, you’re zooming through space at incredible speeds. As just one of all the living creatures on Earth, you’re along for the ride as our planet constantly moves in two major ways. First, consider that the Earth spins around like a top. It’s rotating around the imaginary line which runs from the North Pole to the South Pole through the centre of our planet. Earth completes one full rotation every 24 hours, with a speed of about 1,000 miles per hour at the equator (1,670 km/h).

There are two major reasons. One is that Earth's rotation is smooth. "If you're in a car and you're going at a constant speed on the highway, if you close your eyes and tune out the road noise, you would feel stationary," said Stephanie Deppe, an astronomer and content strategist for the Vera C. Rubin Observatory in Chile. If that car were hitting the brakes repeatedly, you'd know you were in motion. But because it stays at a constant speed, you feel motionless. Put another way, "we know there's no such thing as absolute motion. The only thing that matters is relative motion," said Greg Gbur, a professor of physics and optical science at the University of North Carolina at Charlotte. Earth spins on its axis, taking one day to make a full rotation. While Earth is spinning on its axis, it’s also traveling around the Sun. It takes a year to finish the journey, that is, to make one full revolution and wind up back where we started. Earth hurtles along its path with a whopping average speed of 67,000 miles per hour (107,000 kmh). These speeds are way faster than any vehicle you’ve ever travelled in. So why aren’t you dizzy or flying off into space? Why don’t you even feel the Earth moving?

Think about a time when you do feel motion, such as on a carousel ride at an amusement park. When it speeds up, slows down or turns quickly, your body notices because the motion isn’t smooth. "People like Newton and Galileo pointed this out," he said. "Galileo famously imagined a thought experiment of being in the bowels of a ship. If the ship is sailing on calm water versus the ship being docked at port, you're not going to notice any difference according to the laws of physics." The Earth revolves in an oval-shaped orbit around the Sun while spinning on its slightly tilted axis. In contrast, the Earth’s motion is remarkably steady. It has been spinning on its axis and orbiting the Sun at nearly the same speeds for billions of years, with no sudden jolts or stops. As Earth travels its slightly oval-shaped path around the Sun, its speed does change to be a bit faster when it’s closer to the Sun and a bit slower when it’s farther away. But the changes happen so gradually and smoothly which you don’t feel them at all. And like being in a car or on a ship, everything on Earth is also moving with us. If you roll down a car window on the highway, you get a face full of wind as the car slams you into millions of air molecules. But inside the car with the window up, the air moves with you and you don't feel the wind.

Imagine you’re flying on an airplane that has reached cruising altitude. The engines are humming, you’re soaring through the sky at hundreds of miles per hour, but everything inside feels calm and still. You can walk around, relax and forget you’re traveling at all. That’s because the plane, you and everything else inside it are moving at the same speed, in the same direction. Just as passengers don’t feel the plane’s speed while smoothly cruising, we don’t feel Earth’s movement because we’re traveling at the same speed as our planet. You, your chair, the trees, buildings, oceans, everything is moving together with the Earth. There’s no difference in motion for your body to detect unless Earth were to suddenly speed up, slow down or change direction, and, thankfully, that doesn’t happen. Humans are very small ants on a very big ball. Imagine holding a huge beach ball in your hands. Picture a tiny ant crawling on the surface of that ball. Now, think about us on Earth. We are like that ant, but the ball we’re crawling on is almost 8,000 miles (almost 13,000 km's) wide at the equator. That’s about the distance you’d travel driving from New York to Los Angeles and back to New York.

Likewise, our planet's atmosphere is moving just as fast as we are, so, relative to us, it's stationary. The other reason we don't feel Earth's rotation is gravity. The force of gravity holding us to the Earth is much, much, much stronger than the force that would send us flying outward. Because the Earth is so humongous, any movement feels very slow and gentle to our comparatively minuscule bodies as we stand on its surface. Another reason you don’t notice Earth’s motion is that there are no nearby “landmarks” in space to act as reference points. When you’re in a car on the highway, you see trees, signs or telephone poles rushing by. Those fixed points help your brain register motion. But in space, the stars are so far away that they appear completely still, even though we’re moving relative to them at thousands of miles per hour. Luckily, these high speeds don’t fling us off into space thanks to gravity. Gravity is an invisible force of attraction. It pulls everything on the surface of the planet toward the Earth’s centre. It’s like the Earth is giving us a giant, constant hug, keeping us safely grounded.

The feeling of being pulled outward from a carnival ride, or a car doing doughnuts, is called centripetal acceleration. "It's the feeling of inertia,". Your body wants to keep going in a straight line, but if you're in your car, the car is trying to pull you in a circle. Earth's spin pulls everything outward in the same way, but the force keeping everything stuck to the ground overpowers that pull. Even though we don’t feel the Earth moving, people long ago figured out that it really is by watching the sky carefully. Start with day and night. The Sun appears to rise and set because Earth makes one full rotation on its axis every 24 hours. If Earth weren’t spinning, one side would always face the Sun, and the other would be in darkness. At night, stars and constellations seem to move across the sky as Earth rotates. And their positions in the sky change with the seasons. Our view of the stars changes as we move along our yearly path around the Sun. If everything stayed still, the night sky would never change.

The acceleration of gravity is about 9.8 m/s^2 on the Earth's surface, and the reduction of that due to the rotation of the Earth at the equator, where things are moving the fastest, is about 0.03 m/s^2, which is measurable but really tiny compared to what we feel from gravity itself, so we don't notice it. Then there are the seasons. Earth is tilted on the axis it spins around. Over the course of its orbit of the Sun, Earth’s tilt causes different parts of the planet to get more or less sunlight. That’s why we have summer, winter and everything in between. By seeing Earth spinning and orbiting, satellites and space telescopes have confirmed what astronomers have long deduced. We may not feel it, and we can’t see any obvious landmarks rushing by, but the clues are everywhere. Earth is on the move. And it’s not just Earth, the Sun itself rotates and moves around the centre of our Milky Way galaxy at hundreds of thousands of miles per hour. Nothing in the universe is truly standing still. Everything is in motion, from planets and stars to galaxies around us in the universe.