Oh my days! Midnight comes a fraction sooner as Earth spins faster

Posted: August 1, 2022 by oldbrew in Measurement, solar system dynamics
Tags: ,


As Nasa is reported as suggesting that ‘stronger winds in El Niño years can slow down the planet’s spin’, can we – on the basis of no research at all – nominate La Niña as a suspect here? Just trying to be helpful, as MSN claims: Experts confused after earth spins faster.
– – –
Analysis: Reflecting a recent trend, 29 June was the shortest day on our planet since the 1960s. What’s going on? – wonders The Guardian.
. . .
If time feels tighter than ever of late, blame it on the revolution. On 29 June this year, Earth racked up an unusual record: its shortest day since the 1960s, when scientists began measuring the planet’s rotation with high-precision atomic clocks.

Broadly speaking, Earth completes one full turn on its axis every 24 hours. That single spin marks out a day and drives the cycle of sunrise and sunset that has shaped patterns of life for billions of years.

But the curtains fell early on 29 June, with midnight arriving 1.59 milliseconds sooner than expected.

The past few years have seen a flurry of records fall, with shorter days being notched up ever more frequently. In 2020, the Earth turned out 28 of the shortest days in the past 50 years, with the shortest of those, on 19 July, shaving 1.47 milliseconds off the 86,400 seconds that make up 24 hours. The 29 June record came close to being broken again last month, when 26 July came in 1.5 milliseconds short.

So is the world speeding up? Over the longer term – the geological timescales that compress the rise and fall of the dinosaurs into the blink of an eye – the Earth is actually spinning more slowly than it used to. Wind the clock back 1.4bn years and a day would pass in less than 19 hours.

On average, then, Earth days are getting longer rather than shorter, by about one 74,000th of a second each year. The moon is mostly to blame for the effect: the gravitational tug slightly distorts the planet, producing tidal friction that steadily slows the Earth’s rotation.

To keep clocks in line with the planet’s spin, the International Telecommunication Union, a United Nations body, has taken to adding occasional leap seconds in June or December – most recently in 2016 – effectively stopping the clocks for a second so that the Earth can catch up.

The first leap second was added in 1972. The next opportunity is in December 2022, although with Earth spinning so fast of late, it is unlikely to be needed.

While the Earth is slowing down over the longer term, the situation is messier on shorter timescales. Inside the Earth is a molten core; its surface is a mass of shifting continents, swelling oceans and vanishing glaciers. The entire planet is wrapped in a thick blanket of gases and it wobbles as it spins on its axis. All of these influence the Earth’s rotation, speeding it up or slowing it down, although the changes are essentially imperceptible.

According to Nasa, stronger winds in El Niño years can slow down the planet’s spin, extending the day by a fraction of a millisecond. Earthquakes, on the other hand, can have the opposite effect. The 2004 earthquake that unleashed a tsunami in the Indian Ocean shifted enough rock to shorten the length of the day by nearly three microseconds.

Anything that moves mass towards the centre of the Earth will speed up the planet’s rotation, much as a spinning ice skater speeds up when they pull in their arms. Geological activity that pushes mass outwards from the centre will have the opposite effect and slow down the spin.

How all these different processes come together to affect the length of a day is a question scientists are still wrestling with.

Full article here.
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Update – new record: On July 29, the Earth broke its record for the shortest day. [Or, it broke the pre-June record again].

Comments
  1. oldbrew says:

    Yahoo News suggests the Chandler Wobble may be up to something…
    Mon, August 1, 2022 at 7:01 p.m

    https://ca.finance.yahoo.com/news/earth-spinning-faster-usual-giving-180100817.html

    They also ponder possible leap second headaches for big tech.

  2. catweazle666 says:

    Given conservation of angular momentum, increase in angular velocity indicates reduction in polar moment of inertia.
    One cause of which could be redistribution of mass as water from the equator to the polar regions as ice, thus increasing the mass of the Antarctic and Greenland ice caps, for example.

  3. To make it simple, they have lied about sea level rise and the loss of ice mass, or, they really do not understand much of anything, both are most likely and both are most likely right.
    Since they started the Atomic Clock measuring Time accurately, sea level has gone down and ice volume sequestered in the polar regions and on high mountains nearer the spin axis has grown.

    Worry about sea level rise After, and only After, they need to add more and more leap seconds.

  4. Ron Messick says:

    Here is my take (opinion),

    The Earth’s sphere of gravitational influence (SOI), approximately 145 Earth radiuses, oscillates back and forth (over time) from a distance of 577,777.777-miles and 574,222.222-miles–the mean being 576,000 miles. In other words, it precesses (like axle precession). Accordingly, Earth’s gravitational bubble (mass) also shrinks and expands.

    The SOI has a reciprocal relationship with the Sun of 162:1. Therefore, while Earth’s magnetic field shrinks, the Sun’s magnetic field expands. That causes the Sun’s rotation to slow and Earth’s rotation to speed up.

    The volume of mass does not change. Only the influence. The same thing is happening to all other planets as well. With the Sun having 99% of the mass, the solar system responds in kind.

    Flux tubes (umbilical cords) connect at a planet’s SOI. Therefore, the SOI is where electrical interaction takes place–pulsating at 8-minute intervals.

    These recent papers suggest “Sun’s Magnetic Field 230% Stronger”, and “Swarm probes weakening of Earth’s magnetic field”.

  5. JB says:

    All of this assumes of course that none of the atomic clocks are affected by the sun’s gravitational field, nor the earth’s field fluctuating. I’d like to hear a good explanation how they are not.

  6. oldbrew says:

    Context:

    The Earth was at its furthest from the Sun (aphelion) on July 4th, which means it was orbiting at its slowest speed around that time – only a week after the ‘shortest day since the 1960s, when scientists began measuring the planet’s rotation with high-precision atomic clocks’. Of course that slowing happens every year, but…

    The Sun is also currently moving on its furthest arc from the solar system barycentre since the early 1980s. What, if any, relevance these things have is another matter. Commenter Catweazle mentioned angular momentum for example.
    – – –
    Yahoo gets over-excited about the shortest day EVER (their capitals), meaning…since 1960!

    Using data from the International Earth Rotation and Reference Systems Service, timeanddate.com says 2020 boasted 28 of the world’s shortest days on record since the introduction of the atomic clock in the 1960s made the measurement more scientifically accurate. Earth’s hastened rotation has continued to speed up compared to the average in 2021, leading to 2022’s record for the shortest-ever day recorded. (July 26 nearly eclipsed the record, too.)

    https://ca.finance.yahoo.com/news/earth-spinning-faster-usual-giving-180100817.html

  7. oldbrew says:

    New record on July 29, reported Aug.1.

    https://www.ndtv.com/world-news/earth-completes-rotation-in-less-than-24-hours-smashes-record-again-for-shortest-day-3210536
    – – –
    See popesclimatetheory comment above re. ice mass, and wonder…

  8. Damian says:

    Surely the question that needs answered first is what causes the Earth to rotate? Without knowing the answer to this it is impossible to work out why that rotation has changed.

  9. oldbrew says:

    Damian — Impossible to prove, perhaps.

    But there are some well-known ideas about possible causes of these very small rotation changes.

  10. Paul Vaughan says:

    Ch&llear#1washBRandIn
    …or,well,HRdr.USsiacontroll$theChandlureweatherowebill0RWW0!bull

  11. oldbrew says:

    A few theories get an airing here…

    Changes to the climate or climate systems, such as melting and freezing of glaciers or winds, whose shifting weight pulls on the Earth, The New York Post reported.

    Earthquakes and other seismic activity which move mass toward the center of the Earth, like a spinning person pulling their arms in, The Guardian reported.

    Movement within the Earth’s molten core that shifts mass on the planet, Forbes reported.

    Ocean circulation and pressure on the seabed that pulls on the Earth’s axis, ABC reported.

    The “Chandler Wobble”—a natural shifting of the Earth’s axis due to the planet not being perfectly spherical—could be linked to the spinning speeds, timeanddate.com reported.

    https://phys.org/news/2022-08-earth-faster-usual-experts-shortest.html

  12. Gamecock says:

    ‘Broadly speaking, Earth completes one full turn on its axis every 24 hours.’

    Nope. It turns in 23 hours and 56 minutes. Mr Science Editor confuses an APPARENT rotation with an actual rotation. Pretty lame science editor.

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