# How come the Chandler wobble hasn't dampened out? - question **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [August 1, 2000, 11:35am UTC](https://boards.straightdope.com/t/how-come-the-chandler-wobble-hasnt-dampened-out-question/27689 "2000-08-01T11:35:21Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Ted](https://avatars.discourse-cdn.com/v4/letter/t/db5fbb/32.png) [@Ted](https://boards.straightdope.com/u/Ted)\ **Post date:** [August 1, 2000, 11:35am UTC](https://boards.straightdope.com/t/how-come-the-chandler-wobble-hasnt-dampened-out-question/27689/1 "2000-08-01T11:35:21Z")
How come the Chandler wobble hasn’t dampened out? 03-Dec-1999 Cecil mentions that there are two leading theories as to why this occurs, one is seasonal variations and the other is planetary disturbances, such as earthquakes and the like. My question is, does the Chandler effect (or something similar to it) occur in any of other planets? Are we able to notice such a thing if it does, or do our instruments not have enough accuracy to measure such a thing. If it does occur in any, are we stuck with the same theories still (such as seasonal change)? I ask because if a planet had it, such as mars which has no such seasonal variation (to my knowledge…which I admit is limited on this subject), would not one be able to gauge these two theories better? … oh well… this is the easy way, I guess I’ll go try looking it up myself as well. Thanks for any help. ---
**Author:** ![zut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zut/32/2875_2.png) [@zut](https://boards.straightdope.com/u/zut)\ **Post date:** [August 1, 2000, 12:15pm UTC](https://boards.straightdope.com/t/how-come-the-chandler-wobble-hasnt-dampened-out-question/27689/2 "2000-08-01T12:15:26Z")
Oddly enough, **Ted** , [this thread](http://boards.straightdope.com/sdmb/showthread.php?threadid=31197), started by yours truly, dropped off the bottom of the board just before you posted. Although the links and discussion contained therein don’t directly answer your question, the recently published hypothesis discussed (hypothesis = Chandler wobble is caused by ocean pressure fluctuations) suggests that the Chandler wobble might _not_ occur on other planets. Although, perhaps, a heavy planet like Jupiter might have a dense enough atmosphere to cause pressure fluctuations of enough significance to make the planet wobble. Oh, and let me do my best (if sadly lacking) **Arnold Winkelried** imitiation by 1) being the first one to welcome you to the Straight Dope, and 2) pointing out that the column you are referring to can be found on-line [here](http://www.straightdope.com/columns/991203.html). ---
**Author:** ![Ted](https://avatars.discourse-cdn.com/v4/letter/t/db5fbb/32.png) [@Ted](https://boards.straightdope.com/u/Ted)\ **Post date:** [August 1, 2000, 2:27pm UTC](https://boards.straightdope.com/t/how-come-the-chandler-wobble-hasnt-dampened-out-question/27689/3 "2000-08-01T14:27:04Z")
Thanks for the tip and the welcome! I read the article but one thing does puzzle me about it: > [@](#): > > Gross calculated that two-thirds of the Chandler wobble is caused by ocean-bottom pressure changes \*\* and the remaining one-third by fluctuations in atmospheric pressure. \*\* He says that the effect of atmospheric winds and ocean currents on the wobble was minor. I did not have an opportunity to read Gross’s actual paper and this excerpt for some reason seems to shed a bit of doubt in my mind. For some reason it reads like Gross’s method is lacking. It reads to me as if he was able to account for only 2/3rd’s of the Chandler wobble and just pulled out one of the other hypotheses to account for the rest of it. I’m not saying he is wrong (I am certain he and others have a much greater knowledge of this than myself) but his answer seems to be incomplete by a 1/3rd. Also, to create the regularity of the Chandler wobble, would the fluctuations in the atmospheric pressure need to be in a pattern that coincides with that of the ocean bottom pressure? If they are not wouldn’t there be less of an effect on the Chandler wobble? ---
**Author:** ![Arnold\_Winkelried](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@Arnold\_Winkelried](https://boards.straightdope.com/u/Arnold_Winkelried)\ **Post date:** [August 1, 2000, 4:34pm UTC](https://boards.straightdope.com/t/how-come-the-chandler-wobble-hasnt-dampened-out-question/27689/4 "2000-08-01T16:34:37Z")
Welcome to the SDMB, and thank you for posting your comment. Please include a link to Cecil’s column if it’s on the straight dope web site. To include a link, it can be as simple as including the web page location in your post (make sure there is a space before and after the text of the URL). Cecil’s column can be found on-line at the link provided by zut. ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [August 3, 2000, 5:41am UTC](https://boards.straightdope.com/t/how-come-the-chandler-wobble-hasnt-dampened-out-question/27689/5 "2000-08-03T05:41:22Z")
> [@](#): > > \*Originally posted by Ted \* > \*\*Also, to create the regularity of the Chandler wobble, would the fluctuations in the atmospheric pressure need to be in a pattern that coincides with that of the ocean bottom pressure? If they are not wouldn’t there be less of an effect on the Chandler wobble? > \*\* The patterns wouldn’t have to coincide, but if they weren’t, there might be less of an effect. Dr. Gross has studied the wobble for twenty years, and is apparently dedicated to it. I haven’t seen his paper, but I’m pretty certain he would have accounted for all such effects. There are two wobbles, one at 12 months, and one at 14 months. The 12 month wobble is forced by the seasonal variations, but the 14 month wobble is the Chandler wobble (see [Cecil’s column](http://www.straightdope.com/columns/991203.html)), and it is the natural frequency of the earth. It’s as if the earth is a big tuning fork–if you hit it, it’ll ring at the Chandler wobble frequency, no matter how you hit it. However,after it has started ringing, if you hit it just right, you could stop it from ringing. Calculating the right relationship between the ocean-bottom pressure changes and the wobble was probably the hard part. ---
**Author:** ![Kyberneticist](https://avatars.discourse-cdn.com/v4/letter/k/dc4da7/32.png) [@Kyberneticist](https://boards.straightdope.com/u/Kyberneticist)\ **Post date:** [August 9, 2000, 10:59pm UTC](https://boards.straightdope.com/t/how-come-the-chandler-wobble-hasnt-dampened-out-question/27689/6 "2000-08-09T22:59:36Z")
I’ve been reading a short summary of Gross’ discovery in **Science** magazine. As they explain it, Gross has found an explanation for close to all the wobble. They have a cute diagram which covers all the causes. Melting of ice Atmospheric loading Groundwater Winds Sea level loading Gravitational pull of sun and moon Earthquakes Continental drift Ocean currents Some of these seem more powerful then others, but it sort of makes sense that the slow, persistent work of the winds would keep that tuning fork humming. As for the 1/3, 2/3 thing, as one geophysicst points out, “The oceans are mainly wind-driven, so you have the atmosphere driving the whole thing” The article claims that being able to predict the wobble by measuring those forces that are its source will help in guidance of spacecraft. I had no idea the wobble was significant enough to cause any problems with tracking spacecraft! ---
**Author:** ![Phobos](https://avatars.discourse-cdn.com/v4/letter/p/3d9bf3/32.png) [@Phobos](https://boards.straightdope.com/u/Phobos)\ **Post date:** [August 17, 2000, 9:03pm UTC](https://boards.straightdope.com/t/how-come-the-chandler-wobble-hasnt-dampened-out-question/27689/7 "2000-08-17T21:03:19Z")
from the Sky & Telescope website in July 2000… More than a century after its discovery, a scientist has at last solved the puzzle of the “Chandler wobble.” In 1891 Seth Carlo Chandler determined that Earth’s poles move 6 meters (20 feet) during a 1.2-year cycle. Previous calculations have proven that, without an external force acting, the wobble would dampen after 68 years, yet movement continues. A wide variety of causes have been suggested, but none quite fit the data. Now Richard S. Gross (Jet Propulsion Laboratory) attributes the 433–day polar deviation primarily to pressure fluctuations at the bottom of the ocean, closing the book on this mystery. His paper, to be published in the August 1st Geophysical Research Letters, concludes that variations in atmospheric pressure account for approximately one third of the source of the wobble, while ocean–bottom pressure fluctuations dominate. The mass of the oceans shift in response to changes in temperature, salinity, and atmospheric winds. This movement changes the pressure exerted on the Earth’s crust, causing a wobble. Gross applied numerical models of the ocean to data on the polar motion taken throughout a 10–year period to achieve his results.