# What is Earth rotation: Definition and 24 Discussions

Earth's rotation or Earth's spin is the rotation of planet Earth around its own axis, as well as changes in the orientation of the rotation axis in space. Earth rotates eastward, in prograde motion. As viewed from the north pole star Polaris, Earth turns counterclockwise.
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where Earth's axis of rotation meets its surface. This point is distinct from Earth's North Magnetic Pole. The South Pole is the other point where Earth's axis of rotation intersects its surface, in Antarctica.
Earth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes, and 4 seconds with respect to other, distant, stars (see below). Earth's rotation is slowing slightly with time; thus, a day was shorter in the past. This is due to the tidal effects the Moon has on Earth's rotation. Atomic clocks show that a modern-day is longer by about 1.7 milliseconds than a century ago, slowly increasing the rate at which UTC is adjusted by leap seconds. Analysis of historical astronomical records shows a slowing trend; the length of a day increased about 2.3 milliseconds per century since the 8th century BCE. Scientists reported that in 2020 Earth has started spinning faster, after consistently slowing down in the decades before. Because of that, engineers worldwide are discussing a 'negative leap second' and other possible timekeeping measures.

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1. ### I Speed of the umbra during eclipse vs rate of the Earth's rotation

The earth rotates faster than the moon orbits. Thus, the moon appears to move from East to West each day. The shadow of the moon during an eclipse as it moves along the curved earth makes it move faster and we see it move West to East. My question is If a solar eclipse happens near noon and...
2. ### B How does Earth's rotation affect our movement?

How is it possible that Earth's rotation doesn't affect our relative velocity? In other words, if I walk in the opposite direction of Earth's rotation, shouldn't I reach destinations faster than if I walk in the same direction? Sorry if the terms are not that accurate, I’m an architect!
3. ### B Pound & Rebka Experiment: Earth's Spin Rotation Speed

Earth has an equatorial circumference of 40030.17Km and diameter of 12742Km, in 24 hours you will travel 40030.17Km or 40030.17Km / 24 = 1667.92Km/h in space from the earths spin rotation. If you move 1 Km up in a tall building you are now on a circumference of 40036.45Km, diameter of 12744Km...
4. ### I About the relation between number of sidereal and solar days

Hi all, I've a doubt about the following formula for the number of sidereal vs solar days for a generic planet orbit (e.g. the Earth's orbit around the Sun): $$N_{sid} = N_{sol} + 1$$ Section 1.5 of the book "Foundation of Astrophysics" - B. Ryden shows how to calculate the above equation...
5. ### B Why doesn't the Earth at the equator experience a sonic boom?

The Earth's circumference at the equator is 24,901 miles, or 40.075 million meters. It rotates completely once a day or in 86400 seconds. The speed of sound is 343 m/s and the Earth moves at the equator at 40.075 million m/86400 s = 463.831019 m / s which is clearly faster than the speed of...
6. ### Centrifugal Force Experienced at the Earth's North Pole

If we standing in the equator, then centrifugal force caused by Earth rotation directly balanced by gravity force. But what if we standing in the high altitude or in the pole? In the pole at the distance like 40 km from north pole (so the north pole inside the horizon plane), the gravity have no...
7. N

### Could we find enough mass to slow down the Earth's rotation?

Hi, me and a friend were discussing calendars and how they go wrong. Apparently one orbit around the sun happens during, on average, 365.242189 rotations around Earth's axis. The persian calendar almost nails it, with a 1 sec per year error, because it is based on star observations rather than...
8. ### Earth rotation speed if it was tidal locked to the Sun

Dear Forum, I am filmmaker from Berlin and despite physics focus back in high school I am really bad at it. I am trying to get my head around some ideas I am working on and would kindly ask you for some tiny calculations. I hope this is OK and maybe even fun for someone here? So my questions...
9. ### Centrifugal force on Earth and deviation of free falling obj

Centrifugal force due to rotation of the Earth has among its effects the deviation towards the equator of a ball falling from height ##h## vertically on Earth. I do not understand what is the inertial explanation of this phenomenon. Once the ball is released there is no centripetal force that...
10. ### I Earth rotation different in hemisphere

Why Earth rotates from West to East in southern hemisphere and East to West in northern hemisphere?? Is this true,if yes then explain please.
11. ### Effect of Rotation on the Earth and Planetary Disk(s)

Hello, This problem has probably been done before in different guises but I am struggling, and hoping for help. I am struggling to understand a phenomena which I am assuming is one and the same: Equatorial Bulge of the Earth Flat Plane in which the Planets rotate Protoplanetary disks are flat...
12. ### Can We Outrun a Moving Train? 🚆 Exploring Speed vs. Rotation

if we fly over a moving train at the speed of train can we out run it?? it not, how come we fly at 255m/s when Earth is rotating at 460m/s and we reach from paris to america
13. ### Simulating earth rotation and (excess) Lenght of Day calculation

Hello everybody :smile:, I'm new here and hope you can help me with this problem. I have to simulate the Earth rotation with eulers equations of motion (without external torques at first). I have given: Solution of eulers equation without external torques: \omega = (x, y, z)'...
14. ### Change of weight with faster Earth rotation.

Homework Statement m=55kg r=6400km The Earth's rotation increases so on a bathroom scale, it now reads that you weight 0. how long is 1 "day" on Earth? Homework Equations I keep trying to figure this one out, but with different ways I've tried, I put Fg as 0 and it basically...
15. ### Frictionless world - Earth rotation

If the world was frictionless, would the Earth orbit underneath your feet? Would buildings and things attached to the ground be slamming into you at the same speed as the Earth's rotation?
16. ### Sudden Earth Rotation Deceleration Theory

Just throwing this out there (I'm uncertain if this has been posted before and apologise in advance if I'm just covering old topics) but I have been thinking lately about how a massive change in rotational speed caused possibly by the asteroid presumed to have wiped out the dinosaurs may help...
17. ### Harvesting energy from the earth rotation

Could a gyro be able to harvest the energy from the Earth rotation? If the gyro is locked in space, it must change position relative to the alignment of the earth. This change in position could be the energy output. A gear mechanism is taking energy from the rotating Earth to keep the gyro...
18. ### The Fascinating Possibility of Reversed Earth Rotation

What would happen if the Earth stopped rotating or rotated in the opposite direction? This question has amused me for quite some time and I wanted to share this with you guys...
19. ### Simple Question on Earth Rotation involving Newton III

Simple question with a simple answer, just want a little more description. Newton III states: For every action there is an equal and opposite reaction. As the Earth rotates one way, what's the opposite force that keeps it "balanced"? Inertia? Arrived at the question when was thinking...
20. ### Uncovering the Truth: The Earth's Accelerating Rotation Rate Explained

The (long term) EARTH ROTATION RATE can be in one of 3 states: STABLE : as the Earth is a dynamical system it is unlikely SLOWING : as we can find this is the general information available and corresponds to the science mainstream public position example here ...
21. ### Why can't we stop the Earth's rotation by walking in the opposite direction?

Okay, this stems from a physics argument we had in class today; everyone in the argument (my teacher included), seemed to think that we could stop the Earth's' rotation by walking in the opposite direction saying it was "common sense" however I argued that surely it would have no effect as...
22. ### Earth rotation is slowing down

http://images42.fotki.com/v1375/photos/1/1424948/6925600/EPSON008-vi.jpg 1.[/URL] Homework Statement A man reading a newspaper stating "Earth's rotation is slowing down". there's a fishing bowl next to him. The water in the fishing bowl is leaned towards the right side. What direction is...
23. ### Earth rotation and long flights

I have this question related to the rotation of the earth: Lets say I am in London and I have to fly to New Zealand (non-stop). I can fly to the east and also to the west to get to the destination. If the distances of the two directions are equal, so which route should I choose?
24. ### Perpetum movil that will last as long as earth rotation

Put a giantic gyroscope anywhere, in 24 hours it will have completed a revolution, cranck together the 24 hours rotation with the gyro rotation, if the gyro is heavy enough and the friction low enough it will spin as long as the Earth spins Second option, put a giantic powerball at 45º...