Slowing rotation of the Earth

[trumptor]

<p>I was reading one of the stories on Space.com about the addition of a leap second to the end of 2008 to compensate&nbsp;partially for&nbsp;the slowing of the Earth's rotation and was wondering about the speed of the Earth's rotation throughout time and effects it has had on Earth. </p><p>At some point the Earth was believed to have revolved at twice its present speed which would have given us only a 12 hour day. Assuming that life first started to show up on land around 400 mya how would the different rate of rotation have affected life of the time? Would weather have been noticeably more severe? You'd assume that the planet would've been more of an oblate spheroid due to the angular momentum with deeper oceans at the equator than today and have more violent oceans, or would the effect have been too small to be noticeable? With the centrifugal force being greater in the past would it have have caused material on the surface to weigh less at the equator by any measurable amount to what they weigh today? And out of curiosity, is there any measureable difference to weight at the poles as compared to the equator presently and what percentage is it if anyon has even bothered to measure?</p><p>&nbsp;These were just some things that popped into my head as I was reading the article and would like to hear any ideas if anybody would like to address them.</p> <div class="Discussion_UserSignature"> <p><em><font color="#0000ff">______________</font></em></p><p><em><font color="#0000ff">Caution, I may not know what I'm talking about.</font></em></p> </div>

 

[trumptor]

I know that this was only a 10th of the time going back to when the Earth formed which would have given the length of the day during the time of dinosaurs maybe 23 hours which is not considereably different than today, but say 2 billion or 3 billion years ago. Would there have been easily observable effects from the greater speed of rotation? <div class="Discussion_UserSignature"> <p><em><font color="#0000ff">______________</font></em></p><p><em><font color="#0000ff">Caution, I may not know what I'm talking about.</font></em></p> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I was reading one of the stories on Space.com about the addition of a leap second to the end of 2008 to compensate&nbsp;partially for&nbsp;the slowing of the Earth's rotation and was wondering about the speed of the Earth's rotation throughout time and effects it has had on Earth. At some point the Earth was believed to have revolved at twice its present speed which would have given us only a 12 hour day. Assuming that life first started to show up on land around 400 mya how would the different rate of rotation have affected life of the time? Would weather have been noticeably more severe? You'd assume that the planet would've been more of an oblate spheroid due to the angular momentum with deeper oceans at the equator than today and have more violent oceans, or would the effect have been too small to be noticeable? With the centrifugal force being greater in the past would it have have caused material on the surface to weigh less at the equator by any measurable amount to what they weigh today? And out of curiosity, is there any measureable difference to weight at the poles as compared to the equator presently and what percentage is it if anyon has even bothered to measure?&nbsp;These were just some things that popped into my head as I was reading the article and would like to hear any ideas if anybody would like to address them. <br />Posted by trumptor</DIV><br /><br />Not much of an effect during the time period you describe.</p><p>This geological record is consistent with these conditions 620 million years ago: the day was 21.9 .</p><p>Not really much of a difference.</p><p>As far as a weight difference caused by the rotation rate, that effect is too small to measure. (unless you're really into measuring stuff that makes no difference.)</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Not much of an effect during the time period you describe.This geological record is consistent with these conditions 620 million years ago: the day was 21.9 .Not really much of a difference.As far as a weight difference caused by the rotation rate, that effect is too small to measure. (unless you're really into measuring stuff that makes no difference.) <br /> Posted by MeteorWayne</DIV></p><p>I think what weight difference there is has more to do with the fact that you are closer to the center of mass when you are on the poles than the lack of centripetal force at the equator. </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[dragon04]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Not much of an effect during the time period you describe.This geological record is consistent with these conditions 620 million years ago: the day was 21.9 .Not really much of a difference.As far as a weight difference caused by the rotation rate, that effect is too small to measure. (unless you're really into measuring stuff that makes no difference.) <br /> Posted by MeteorWayne</DIV></p><p>I think there are maybe subtle but very important differences. I'm certainly no biologist, but breeding cycles would have been more rapid, I should think. That might not sound like much until one considers what impact more rapid breeding cycles may have had on mutation and evolution as a result.</p><p>Higher (and lower) tides coming (and going out) at more frequent intervals would have their effects as well. We're locked into circadian rhythms and certainly as the length of the day has changed over time, so have we. At least I think so.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I think there are maybe subtle but very important differences. I'm certainly no biologist, but breeding cycles would have been more rapid, I should think. That might not sound like much until one considers what impact more rapid breeding cycles may have had on mutation and evolution as a result.Higher (and lower) tides coming (and going out) at more frequent intervals would have their effects as well. We're locked into circadian rhythms and certainly as the length of the day has changed over time, so have we. At least I think so.&nbsp; <br />Posted by dragon04</DIV><br /><br />The point was the difference between 600 MY ago and now is only about 10%, (22 hr vs 24 hr) relatively small. If you go back billions of years, I agree the effect would have been more significant, but most life at that time was unicellular, so it's unclear what that time difference would have meant to "them". <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[dragon04]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The point was the difference between 600 MY ago and now is only about 10%, (22 hr vs 24 hr) relatively small. If you go back billions of years, I agree the effect would have been more significant, but most life at that time was unicellular, so it's unclear what that time difference would have meant to "them". <br /> Posted by MeteorWayne</DIV></p><p>Too bad (or maybe they ARE) JPL or someone didn't do a study on the effect of having Mars rover drivers living a Martian Day as opposed to an Earth day. There's a relatively small difference between a Sol on Mars and an Earth day, but over time, and yes, due in part to Mars' orbital period, that slightly longer day may not be so insignificant.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>