March 4, 2010--The Earth Moved (Literally)
At this point in my life feeling the earth move--whatever the cause--is a headline. So to learn that it actually moved the other day is a big deal.
Yes, the earth is in constant motion. It rotates on its own axis every 24 hours and circles the sun every 365 days. And the entire solar system and galaxy of which we are a miniscule part speeds through the larger universe at warp speed.
But this is not the movement I am talking about. And sad to say, that movement was the result of a tragedy--the recent earthquake in Chile. Further, the earth movement I am referring to is not the sudden cataclysmic one caused by the slippage of one monster tectonic plate, the Nazca Plate, 24 miles underground pushed itself further under the one upon which Chile and much of South America rests--the South American Plate. One result of this relentless movement is that over eons the South American Plate has been so powerfully upthrusted by the Nazcan that over the millennia the Andes came into majestic being.
No, what I am now pondering is how this unfathomable event shifted the very axis of our earth. Moved the entire planet. Minutely, to be sure, but measurably nonetheless. Enough, according to NASA scientists, so that an earth day has been shortened by about one-millionth of a second. For those who like more precision, by an estimated 1.26 microseconds. (See New York Time's article linked below,)
How could this be? Isn't the tilt of the earth's axis an immutable 23.5 degrees? And thus aren't the number of hours in a day eternal? Twenty-four? Again more specifically, 86,400 seconds? Or, if you prefer, 86,000,000,000,000 microseconds?
Far from it. Periodically, over the billions of years of the earth's existence the distribution of mass on the earth has been rearranged--as ice ages came and went more or less ice was concentrated at the poles; more or less water was distributed throughout the world's oceans; and closer to the Chilean event, shifts occurred in the location of the land masses (more of the Nazca Plate than before last week moved under the South American Plate). And all have had an affect on the angle at which the earth's axis (the line around which the earth rotates) is tilted from the horizontal--the horizontal being the direction or plane in which the earth circles the sun. And this in turn has altered the length of our day.
In fact, the axial angle as it is called, varies from 22.1 and 24.5 degrees. This oscillation occurs quite regularly every 42,000 years. And as it occurs, the rotational spin of the earth either speeds up or, as now, slows down. The more upright the longer the day; the more tipped, the shorter. The earthquake in Chile added to the tipping and thus the slowing.
While I was researching some of this, I discovered that it is not only tectonic events that contribute to the earth's tilt. Global cooling and global warming do so as well in that during those times there are huge shifts in the distribution of water and ice on the globe. One thing that is currently under speculation is the affect the current warming is having on the axial angle. As more polar ice melts and turns to water, more slowing will inevitably occur which in turn will lead to transglobal climactic changes.
An here I was only wondering about that 1.26 microseconds, feeling happy that time itself is slowing down and maybe I'm not as old as I think I am. But then again . . .
Yes, the earth is in constant motion. It rotates on its own axis every 24 hours and circles the sun every 365 days. And the entire solar system and galaxy of which we are a miniscule part speeds through the larger universe at warp speed.
But this is not the movement I am talking about. And sad to say, that movement was the result of a tragedy--the recent earthquake in Chile. Further, the earth movement I am referring to is not the sudden cataclysmic one caused by the slippage of one monster tectonic plate, the Nazca Plate, 24 miles underground pushed itself further under the one upon which Chile and much of South America rests--the South American Plate. One result of this relentless movement is that over eons the South American Plate has been so powerfully upthrusted by the Nazcan that over the millennia the Andes came into majestic being.
No, what I am now pondering is how this unfathomable event shifted the very axis of our earth. Moved the entire planet. Minutely, to be sure, but measurably nonetheless. Enough, according to NASA scientists, so that an earth day has been shortened by about one-millionth of a second. For those who like more precision, by an estimated 1.26 microseconds. (See New York Time's article linked below,)
How could this be? Isn't the tilt of the earth's axis an immutable 23.5 degrees? And thus aren't the number of hours in a day eternal? Twenty-four? Again more specifically, 86,400 seconds? Or, if you prefer, 86,000,000,000,000 microseconds?
Far from it. Periodically, over the billions of years of the earth's existence the distribution of mass on the earth has been rearranged--as ice ages came and went more or less ice was concentrated at the poles; more or less water was distributed throughout the world's oceans; and closer to the Chilean event, shifts occurred in the location of the land masses (more of the Nazca Plate than before last week moved under the South American Plate). And all have had an affect on the angle at which the earth's axis (the line around which the earth rotates) is tilted from the horizontal--the horizontal being the direction or plane in which the earth circles the sun. And this in turn has altered the length of our day.
In fact, the axial angle as it is called, varies from 22.1 and 24.5 degrees. This oscillation occurs quite regularly every 42,000 years. And as it occurs, the rotational spin of the earth either speeds up or, as now, slows down. The more upright the longer the day; the more tipped, the shorter. The earthquake in Chile added to the tipping and thus the slowing.
While I was researching some of this, I discovered that it is not only tectonic events that contribute to the earth's tilt. Global cooling and global warming do so as well in that during those times there are huge shifts in the distribution of water and ice on the globe. One thing that is currently under speculation is the affect the current warming is having on the axial angle. As more polar ice melts and turns to water, more slowing will inevitably occur which in turn will lead to transglobal climactic changes.
An here I was only wondering about that 1.26 microseconds, feeling happy that time itself is slowing down and maybe I'm not as old as I think I am. But then again . . .
posted by Steven Zwerling at
6:09 AM
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