Go Back   IceInSpace > General Astronomy > Astronomy and Amateur Science

Reply
 
Thread Tools Rate Thread
  #1  
Old 29-03-2024, 08:46 PM
gary
Registered User

gary is offline
 
Join Date: Apr 2005
Location: Mt. Kuring-Gai
Posts: 5,981
Nature :- A global timekeeping problem postponed by global warming

In astronomical calculations we have to account for leap seconds. Since 1972, the SI unit for the second is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.

That's a mouthful, but this definition and chosen number of cycles is no accident. Oscillations of the caesium-133 atom are at the heart of how atomic clocks maintain time and the 9,192,631,770 oscillations was chosen to make atomic time, known as TAI, to be as close as possible to the historical second of observed solar time known as UT1.

The Earth's rotation speed is not constant and measurably changes very slightly over time mainly because of the slowing down of the Earth's rotation due to tidal friction with the Moon.

A body with the quirky sounding name of the Earth Rotation Service in Paris keeps track of the difference between atomic time (TAI) and solar time (UT1). They publish the time difference every few days, typically in the order of tens of milliseconds. The official world time keeping standard is UTC. It ticks at the frequency of atomic time but is adjusted when the need arises to stay within 0.9 seconds of solar time, UT1. So now and then we insert leap seconds into the world's time keeping, literally a 61st second to a minute.

Now in a paper published in Nature on 27th March 2024, researchers have shown that after accounting for other phenomena, such as the changes in the Earth's molten core, that another factor in the accounting is due to climate change. The melting polar icecaps is causing the angular velocity of the Earth to decrease rapidly.

It's not about to change day to day life for anyone soon. But still pretty screwed up a notion that we burnt so much fossil fuels in the period starting with the Industrial Revolution that we managed to measurably change the Earth's rotational velocity.

Link to paper, "A global timekeeping problem postponed by global warming",
by Duncan Carr Agnew Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA.

https://www.nature.com/articles/s415...uXCBtEF1oj-aJi
Reply With Quote
  #2  
Old 31-03-2024, 01:54 PM
Leo.G (Leo)
Registered User

Leo.G is offline
 
Join Date: Nov 2016
Location: Lithgow, NSW, Australia
Posts: 658
If I can remember all of that I have a valid excuse for being late, LOL


If fossil fuel caused so much damage imagine what spontaneous igniting Tesla batteries are going to do for the environment?
No, I'm not disputing the facts but I think we need to advance beyond toxic lithium. The masses don't seem to understand the landfill and potential pollution problem with the current generation of batteries.
I'd like to see further development of ultra/super capacitors used in conjunction with batteries. At one time Honda, Toyota and the CSIRO (don't quote me on this my memory is crap) were working on carbon nano-fibre ulta capacitors in conjunction with batteries and getting good results
There's the new sodium based batteries apparently now available on the market but their capacity is nowhere near the density of lithium.


Then there's China and India, their pollutant output is HUGE, they just don't seem to care.
Reply With Quote
  #3  
Old 31-03-2024, 04:25 PM
Crater101's Avatar
Crater101 (Warren)
Mostly Harmless

Crater101 is offline
 
Join Date: Jul 2020
Location: Bathurst, NSW
Posts: 685
Quite a bit here was news to me. Sincere thanks for sharing!
Reply With Quote
  #4  
Old 26-05-2024, 04:10 PM
morls (Stephen)
Space is the place...

morls is offline
 
Join Date: Sep 2009
Location: Melbourne
Posts: 704
Thanks for this post Gary, very interesting.

Does this mean there is an enormous energy transition from angular momentum to some other form taking place? I'm simplistically imagining the kinetic/rotational energy reducing as momentum decreases.

I'm also wondering if the angular velocity of the earth would increase if earth went through a period of cooling, and the polar caps gained more mass?
Stephen
Reply With Quote
  #5  
Old Today, 07:51 PM
bgilbert (Barry gilbert)
barryg

bgilbert is offline
 
Join Date: Oct 2015
Location: tamworth
Posts: 66
Several hundred million years ago we had "snowball Earth". This situation existed for some millions of years. Prior to snow ball earth the planet was hotter than the present. After snow ball earth the earth was hotter than the present. It would appear that huge variations in climate existed before the industrial revolution started the CO2 increase that some people stress over so much.
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 11:03 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Bintel
Advertisement