Is spin of earth constant ?

In summary, the Earth's rotation rate is not constant, but it undergoes secular, periodic, and seemingly random changes.
  • #1
Is spin of Earth constant during year ?

(don't implant friction(s) )
 
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  • #2
You mean it's rotation on it's axis (ie length of the day)?
Mostly yes, it's slowing down slightly but at a constant rate - it doesn't vary much during the year.
(ok on very very small scale it varies with every storm, snowfall and earthquake)

If you mean the speed around the sun - then this changes summer-winter with the different distance from the sun.
 
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  • #3
In a sense, it is. It changes very gradually. However, the rotation period becomes shorter as we look back in our Earth's history. The planet used to rotate a lot faster, because of the gravitational pull of the moon. The moon used to be revolving closer to Earth. The closer it was, the faster the revolution of the moon, and hence, the faster the rotation of the Earth. The moon is moving away, causing us to slow down as it does so. So, as time goes on, our rotation will slow down.
 
  • #4
No. The Earth's rotation rate is not constant. The rotation rate undergoes secular, periodic, and seemingly random changes.

The secular changes result from the Earth transferring angular momentum to the Moon. This is a very real, measurable effect. The length of one day (midnight to midnight) is increasing by about 2.3 milliseconds per century.

The periodic effects result from seasonal changes such as snow and ice building up in the Northern hemisphere during the winter and melting during spring/summer. This reduces the Earth's moment of inertia tensor during Northern hemisphere winter and increases it during summer. Since the Northern hemisphere is mostly land and the Southern mostly water, it is the seasons in the Northern hemisphere that drive these changes.

Even little things like earthquakes have a measurable effect on the length of day. Scientists don't know how to predict all these little changes exactly, but they try. After the fact, they can report the measured changes. The International Earth rotation and Reference systems Service (IERS) publishes forecasts of and measured values of DUT1 (google that term) on a regular basis.
 
  • #5
A nice little graph, courtesy Wikipedia:

600px-Leapsecond.ut1-utc.svg.png


This graph shows the difference between UT1 and UTC. The horizontal axis is in years. The vertical axis is DUT1=UT1-UTC (in seconds). If you spliced the ends of each descending section together you would get a graph of the difference between UT1 and Atomic Time (less a constant; TAI-UTC is presently 34 seconds). Subtract another 32.184 seconds and you get the additive inverse of Delta-T, the difference between Terrestrial Time and UT1. Ignoring those leap second discontinuities, the graph isn't a straight line.

The US Naval Observatory provides the timing services for the IERS. Website: http://maia.usno.navy.mil [Broken].
 
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1. What is the spin of the Earth?

The spin of the Earth refers to the rotational motion of the planet around its own axis. This motion is responsible for the day and night cycle on Earth.

2. Is the spin of the Earth constant?

No, the spin of the Earth is not constant. It undergoes small variations due to factors such as changes in the distribution of mass within the planet and the gravitational pull of other celestial bodies.

3. How do scientists measure the spin of the Earth?

Scientists use techniques such as Very Long Baseline Interferometry (VLBI) and satellite laser ranging to accurately measure the spin of the Earth. These methods involve tracking the positions of distant quasars and satellites to determine the Earth's rotation rate.

4. Can the spin of the Earth change over time?

Yes, the spin of the Earth can change over time. This is due to various factors such as the redistribution of mass within the planet, changes in the Earth's orbit, and the influence of other celestial bodies.

5. What would happen if the spin of the Earth suddenly stopped?

If the spin of the Earth were to suddenly stop, it would have catastrophic effects on the planet. The atmosphere and oceans would continue to move at high speeds, causing devastating storms and tsunamis. The lack of rotational motion would also affect the Earth's magnetic field, leading to increased exposure to harmful solar radiation.

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