{"id":907260,"date":"2026-09-27T10:20:17","date_gmt":"2026-09-27T10:20:17","guid":{"rendered":"https:\/\/www.newsbeep.com\/au\/907260\/"},"modified":"2026-09-27T10:20:17","modified_gmt":"2026-09-27T10:20:17","slug":"a-gravitational-battle-within-the-earth-is-changing-the-length-of-days","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/au\/907260\/","title":{"rendered":"A Gravitational Battle Within the Earth Is Changing the Length of Days"},"content":{"rendered":"

Earth’s days are not exactly the same length. Scientists have been recording small variations in for decades. These changes are minuscule\u2014sometimes just a few milliseconds\u2014and mostly imperceptible, but scientists are keen to understand them as they point to a much more monumental change: Our planet\u2019s rotation speed<\/a> is shifting.<\/p>\n

Scientists have already pinpointed a handful of compounding causes. Fluctuations in the atmosphere<\/a> and oceans<\/a> can slightly speed up or slow down the Earth\u2019s rotation; major earthquakes<\/a> can redistribute part of the planet\u2019s mass; and by depositing enormous amounts of water into the oceans, melting continental ice<\/a> is also a factor.<\/p>\n

These influences account for some of the more sudden and recent changes, but on a several decades-long timescale, some of the variation appears to originate from a source much deeper within the Earth. Beneath our planet\u2019s rocky mantle<\/a> lies the outer core\u2014a 1,400 mile thick layer of ultra-hot liquid metal that is in constant motion. As these flows change, they can slightly alter the speed at which the rest of the planet rotates.<\/p>\n

However, how these forces are transmitted from one region to another has remained a mystery. Friction between the core and the mantle is too weak, so geologists have been searching for other mechanisms operating in the Earth\u2019s interior.<\/p>\n

In a new study<\/a> published this week in Nature, researchers believe they have identified one of these hidden gears. They propose that the gravity of the inner core pushes rotation in one direction, while other interactions between the core and the mantle oppose it. The result of this competition, accumulated over decades, would be small accelerations and decelerations in the planet\u2019s spin.<\/p>\n

The idea is based on the fact that the inner core does not rotate at the same rate as the rest of the planet, causing it to become slightly misaligned with certain mass irregularities in the mantle. But the core \u201cwants to be aligned,\u201d Mathieu Dumberry, a geophysicist at the University of Alberta involved in the study, said in a press release<\/a>. What this means is that gravity tries to pull the layers of the inner Earth back into their more harmonic position, which influences\u2014albeit minutely\u2014the rotation of the planet\u2019s surface.<\/p>\n

The authors reconstructed how this interaction influenced Earth\u2019s spin between 1964 and 2019 using seismic estimates of the inner core\u2019s rotation and models of liquid metal<\/a> flows in the outer core. Their gravitational model<\/a> closely reproduced both the timing and the magnitude of real gradual changes that had been observed over the decades.<\/p>\n

Other yet-unknown factors are likely involved, but this proposal unravels a major component of our variable days. The model also didn\u2019t account for all the forces competing involved, but it didn\u2019t need to to produce a compelling result. Because it might be a tug-of-war, Dumberry said, but \u201cgravity still wins.\u201d<\/p>\n

This story originally appeared in WIRED en Espa\u00f1ol<\/a> and has been translated from Spanish.<\/p>\n","protected":false},"excerpt":{"rendered":"Earth’s days are not exactly the same length. Scientists have been recording small variations in for decades. These…\n","protected":false},"author":2,"featured_media":907261,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[64,63,129,2255,10588,3189,2569,128,285],"class_list":["post-907260","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-au","tag-australia","tag-earth","tag-earth-science","tag-geology","tag-gravity","tag-planets","tag-science","tag-space"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/907260","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=907260"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/907260\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/907261"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=907260"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=907260"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=907260"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}