Timeline for How long was a day at the creation of Earth?
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12 events
| when toggle format | what | by | license | comment | |
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| Jul 6, 2012 at 4:48 | comment | added | MadScientist | @dmckee There is a lack of data here. This is my best estimate given the amount of data provided. It might be a decent lower bound (assuming the Earth is generally rotating slower with nothing to crazy happening periodically- like huge meteorites hitting it a making it spin significantly faster). How fast do you think the earth was rotating at its fastest in the distant past? If you answer that then the average of that rate with the modern one would probably give a good estimate. | |
| Jul 6, 2012 at 4:38 | comment | added | dmckee --- ex-moderator kitten | The data the OP linked show a figure which could be misread as the value he quotes. I believe I've read that the day was shorter by on order of one hour during the era of the dinosaurs which suggests a rate of change more like your reference than the OP's. But just noticing that the OP has the wrong figures does not answer the question. | |
| Jul 6, 2012 at 4:31 | comment | added | MadScientist | If the rate of change is changing, the reasonable thing to do would be to take the average rate of change. There could be physical reasons to weight some rates higher. | |
| Jul 6, 2012 at 4:27 | comment | added | MadScientist | But, he said "each day is 1 second longer every 1.5 years" and that is false. Are you saying that rate was accurate at some time? | |
| Jul 6, 2012 at 4:24 | comment | added | dmckee --- ex-moderator kitten | The effect is inherently a tidal one (the moon is pushed further away at the cost of some of the Earth's angular momentum), and as such was larger in the distant past when the moon was closer. The article you link takes data (nice methodology, BTW) for all of 2500 years which is a drop in the bucket. | |
| Jul 6, 2012 at 4:20 | comment | added | dmckee --- ex-moderator kitten | You have failed to understand the question. The value given is the rate of slowing in this epoch, not some permanently fixed global value. | |
| Jul 6, 2012 at 4:19 | comment | added | MadScientist | Although the rate is changing, you can take the average and this should give you a good estimate: "The average day has grown longer by between 15 millionths and 25 millionths of a second every year" (popsci.com/jessica-cheng/article/2008-09/…) | |
| Jul 6, 2012 at 4:17 | history | edited | MadScientist | CC BY-SA 3.0 |
added 281 characters in body
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| Jul 6, 2012 at 4:10 | comment | added | Cameron Aziz | precisely why its not linear... | |
| Jul 6, 2012 at 4:08 | comment | added | MadScientist | The numbers don't make sense btw. A day cannot be more than 60*60*24 seconds shorter. This calculation implies that a day in the past was 3 billion seconds shorter than a day today (days were negative length?). | |
| Jul 6, 2012 at 4:02 | comment | added | Cameron Aziz | shorter = typo. also, as I stated, that assumption is inheritly false. The rate of change isn't constant. I have added a link to the rate of change for the last 50 years. | |
| Jul 6, 2012 at 3:55 | history | answered | MadScientist | CC BY-SA 3.0 |