{"id":633767,"date":"2026-09-23T19:20:13","date_gmt":"2026-09-23T19:20:13","guid":{"rendered":"https:\/\/www.newsbeep.com\/ie\/633767\/"},"modified":"2026-09-23T19:20:13","modified_gmt":"2026-09-23T19:20:13","slug":"something-deep-inside-earth-keeps-messing-with-the-length-of-our-days","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ie\/633767\/","title":{"rendered":"Something Deep Inside Earth Keeps Messing With the Length of Our Days"},"content":{"rendered":"

For practical purposes, we say that one day\u2014the time it takes for Earth to rotate once on its axis\u2014equates to 24 hours. In reality, different factors across different timescales influence<\/a> how quickly our planet turns, which scientists have yet to fully understand.<\/p>\n

But new findings<\/a>, published today in Nature, may finally solve at least one of these outstanding mysteries, namely how Earth\u2019s rotation changes every couple of decades. According to the study, the multidecadal changes in Earth\u2019s behavior come from deep inside our planet. Three mechanisms\u2014gravitational, electromagnetic, and topographic coupling\u2014essentially compete with one another to speed up or slow down Earth\u2019s rotation over several decades. Specifically, gravitational coupling, or a gravity \u201ctorque\u201d between Earth\u2019s inner core and mantle, creates tiny changes that are pushed back by the other two mechanisms, explained Huifeng Zhang<\/a>, the study\u2019s first author.<\/p>\n

\u201cWhat I find particularly exciting is that these different pieces of information can come together to provide a more coherent picture of Earth\u2019s deep interior, a region that is extremely difficult to observe directly,\u201d Zhang, a PhD student at the University of Alberta in Canada, told Gizmodo.<\/p>\n

Timely changes <\/p>\n

Scientists studying Earth\u2019s rotation will likely investigate different factors, depending on the timescale they\u2019re thinking about. For example, shorter-term variations are controlled by changes in the atmospheres and oceans, Zhang explained. On the other hand, tidal interactions with the Moon occur over millions of years. The relative mid-range timescales of several decades\u2014which the new paper covers\u2014remained a mystery for a long time, according to Zhang.<\/p>\n

\u201cOur main motivation was therefore to investigate the relative contributions of different core-mantle coupling mechanisms to the observed variations,\u201d she added. To do so, Zhang and her co-author and supervisor, Mathieu Dumberry, referenced previous work from 1988 that demonstrated how exchanges of angular momentum between Earth\u2019s core and mantle could influence Earth\u2019s rotation.<\/p>\n

The pair picked out three possible mechanisms that likely influenced this exchange. Gravitational coupling refers to the gravitational interactions between the inner core and the mantle and how quickly the former deforms. Electromagnetic coupling concerns the conductivity and thickness of a specific layer at the base of the mantle. Finally, topographic coupling depends on any irregularities that emerge along the core-mantle boundary.<\/p>\n

These models go deep <\/p>\n

For the study, Zhang and Dumberry ran statistical models to assess different combinations of these factors against real observations over the past six decades. As a result, they were able to find that gravitational coupling exerted the most influence on Earth\u2019s rotation changes. Meanwhile, the other two mechanisms appeared to serve as a sort of buffer against these changes.<\/p>\n

\u201cThis suggests that interactions deep inside Earth can play an important role in speeding up or slowing down its rotation over several decades,\u201d Zhang explained. Because each mechanism depends on physical properties that aren\u2019t \u201cyet well understood,\u201d the findings also \u201cprovide valuable constraints on several properties of Earth\u2019s deep interior,\u201d she added.<\/p>\n

Observational data show that, between the early 1970s and 2021, core-driven mechanisms very slightly altered the length of the day by several milliseconds\u2014a tiny but tangible change. Overall, Earth\u2019s days have been growing shorter over time.<\/p>\n

Our fickle planet <\/p>\n

Again, the latest work deals with variations on the scale of decades. Because so many factors contribute to Earth\u2019s rotational changes, the new study alone is part of a bigger puzzle in understanding the behavior of our ever-changing planet. Currently, Zhang is investigating whether these mechanisms might also have a hand in another observation, or a six-year oscillation in the length of day.<\/p>\n

\u201cEven tiny changes in Earth\u2019s rotation can provide valuable information about processes occurring thousands of kilometers beneath our feet,\u201d she said. \u201cBy combining these improved observations with measurements of Earth\u2019s rotation and inner core motion, we hope to develop a more detailed picture of how Earth\u2019s deep layers interact and how motions thousands of kilometers beneath the surface subtly change the length of our day.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"For practical purposes, we say that one day\u2014the time it takes for Earth to rotate once on its…\n","protected":false},"author":2,"featured_media":633768,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[40954,3224,61,60,13956,82,247],"class_list":["post-633767","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-atmospheric-science","tag-earth","tag-ie","tag-ireland","tag-planetary-science","tag-science","tag-space"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/633767","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=633767"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/633767\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/633768"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=633767"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=633767"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=633767"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}