Are years getting longer

[Saber]

Are they ??

 

And if yes    why ?

Decrease in rotational speed ?     Or  increase in  orbital radius ??

 

Thanx.........

[swansont]

What’s your source? And what year is being given (tropical year, anomalistic year, sidereal year)

The tropical year varies owing to the earth wobbling, and the anomalistic year varies owing to variations in the orbit.

 

https://www.jacksonville.com/story/news/reason/2017/02/25/think-you-know-how-many-days-year-think-again/15744336007/

[Saber]

1 hour ago, swansont said:

What’s your source? And what year is being given (tropical year, anomalistic year, sidereal year)

 

Tropical  year
Source  :Wiki

[mistermack]

How is a year measured? 

Off the top of my head, I would measure it by starting the clock when the Sun, Earth and the most distant Galaxy that's practical to use, are perfectly lined up, and then stop the clock next time that happens. (using the best kit available)

Is that how it's done, or something like it? 

[swansont]

24 minutes ago, Saber said:

Tropical  year
Source  :Wiki

I was hoping for a link.

13 minutes ago, mistermack said:

How is a year measured? 

Off the top of my head, I would measure it by starting the clock when the Sun, Earth and the most distant Galaxy that's practical to use, are perfectly lined up, and then stop the clock next time that happens. (using the best kit available)

Is that how it's done, or something like it? 

It depends on which year you're using.

----

 

Tropical year

https://en.wikipedia.org/wiki/Tropical_year

And, gosh, right before that table, the article says

When tropical year measurements from several successive years are compared, variations are found which are due to the perturbations by the Moon and planets acting on the Earth, and to nutation.

So I'm going to go out on a limb and say that the variations are from perturbations by the moon and nutation.

 

But no, the year isn't getting longer - this is not a long-term trend, it's short-term among the fluctuations

2007-08 was several minutes shorter than the above table - 365d 5h 40m 45s

https://www.timeanddate.com/astronomy/tropicalyearlength.html

[Saber]

16 minutes ago, swansont said:

But no, the year isn't getting longer - this is not a long-term trend, it's short-term among the fluctuations

2007-08 was several minutes shorter than the above table - 365d 5h 40m 45s

https://www.timeanddate.com/astronomy/tropicalyearlength.html

Thank  you  very  much......

[Airbrush]

When I Googled the op question, I found this article which says days are getting longer, and it is a mystery why.

"Atomic clocks, combined with precise astronomical measurements, have revealed that the length of a day is suddenly getting longer, and scientists don't know why.  

"Over the past few decades, Earth's rotation around its axis – which determines how long a day is – has been speeding up. This trend has been making our days shorter; in fact, in June 2022 we set a record for the shortest day over the past half a century or so.  But despite this record, since 2020 that steady speedup has curiously switched to a slowdown – days are getting longer again, and the reason is so far a mystery."

Earth's Days Are Mysteriously Getting Longer, Scientists Say : ScienceAlert

Edited April 19, 2023 by Airbrush

[swansont]

29 minutes ago, Airbrush said:

When I Googled the op question, I found this article which says days are getting longer, and it is a mystery why.

"Atomic clocks, combined with precise astronomical measurements, have revealed that the length of a day is suddenly getting longer, and scientists don't know why.  

"Over the past few decades, Earth's rotation around its axis – which determines how long a day is – has been speeding up. This trend has been making our days shorter; in fact, in June 2022 we set a record for the shortest day over the past half a century or so.  But despite this record, since 2020 that steady speedup has curiously switched to a slowdown – days are getting longer again, and the reason is so far a mystery."

Earth's Days Are Mysteriously Getting Longer, Scientists Say : ScienceAlert

You might note this is days, not the year, and the scale is milliseconds, i.e. much smaller than what was described in the OP

The “mystery” is which contributions are primarily responsible. The mechanism is well-known - conservation of angular momentum* If the moment of inertia changes, the rotational speed will also change to keep the momentum constant. Mass distribution changes cause the moment to change. These can come from melting of arctic ice, droughts, changes in shape of the earth’s crust IIRC there are dozens of terms in the earth rotation model. Some are not predictable. You have to model them as they happen.

The rotation has been known to speed up and slow down for as long as we’ve had precise enough data

*there’s a long-term effect which is exerting a torque, thus lowering the angular momentum: tidal breaking from the moon.