Sounds like a good read for a lazy day, yes ?
Until you read it and realize that this is the kind of stuff that AGW types write:
One Earth day is about 24 hours long. Over the course of a year, the length of day normally changes gradually by one millisecond. It increases in the winter, when the Earth rotates more slowly, and decreases in the summer, Gross has said in the past.Whose winter/summer has such a profound effect on the length of day ? Northern Hemisphere or Southern Hemisphere ?
There is actually a link in that "length of day" stuff that has an even smarter article on how the day is getting longer because humans are polluting the planet.
Another bright spot in the article that defies mathematics, and probably physics, is:
The 9.1 Sumatran earthquake in 2004, which set off a deadly tsunami, should have shortened Earth's days by 6.8 microseconds and shifted its axis by about 2.76 inches (7 cm, or 2.32 milliarcseconds).
8.8 earthquake that struck Chile....1.26 milliseconds.....also found that it should have moved Earth's figure axis by about 3 inches (8 cm or 27 milliarcseconds).
That's right. Moving the Earth's figure axis, it's mass balance, by 12.5% more caused a move of 18,529.4% more.
Amazing!
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5 comments:
Concerning the model of the effects of the quake, you have your figures/units wrong. The axis has been modeled to have shifted by 2.7 milliarcseconds with an effect of shortening our day by 1.26 microseconds. Which an order of magnitude (in reference to time) smaller than your proposed 1.26 milliseconds.
Excellent point.
Thanks for pointing out my error.
The question of whether or not that defies physics remains, since I am clearly not the goto guy for that.
I remain amazed by how much more an 8.8 quake can move the Earth off of it's figure axis than can a 9.1 that was approximately 3 times as powerful.
Like real estate it must all be location, location, location
Common Cents: Thanks I am more than happy to link to you.
I read that same article elsewhere and got stuck at the same spot (regarding the winter and summer thing and how it "rotates" more slowly.) You are correct. The wording is wrong. The winter they are referring to is the Northern Hemisphere's winter, and the Earth doesn't rotate more slowly, the speed of it's orbit around the sun is slower in the winter due to it's elliptical path. That's completely different. Thank you for being clever and noticing that their wording was wonky. Here's a link that explains it better than I can. http://blogs.rep-am.com/worth_reading/2010/03/02/mystery-solved/
Great site Jennifer, thanks.
I especially love their take, "There’s a simpler answer: The earth spins slower in winter just to annoy us."
We are such "Hemisphere-ists" to consider "our" Hemisphere as superior.
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