Here\u2019s what you will learn when you read this story:<\/p>\n
Gravitational anomalies detected by NASA and the German Aerospace Center\u2019s GRACE satellites confused scientists for years.<\/p>\n
These anomalies are fluctuations in gravity, and while they were suspected to come from the ocean, something wasn\u2019t making sense.<\/p>\n
It is now thought that the source is a phase transition in which one crystalline mineral\u2019s structure is altered.<\/p>\n
Even Earth can feel alien<\/a> sometimes. Strange gravity signals indicating shifts in the gravitational field<\/a> (picked up by observatories in the past) were definitely coming from our plan, but where exactly they originated was unknown. This may sound like it\u2019s not that deep, but it turned out to be literally deeper than anyone thought.<\/p>\n Though these anomalies, known as \u201cgeomagnetic jerks,\u201d were detected by NASA and the German Aerospace Center (DLR) through their Gravity Recovery and Climate Experiment (GRACE) collaboration years ago, the cause has eluded scientists until now. When a team of researchers \u2014lead by Charlotte Gauge Gouranton of Universit\u00e9 Paris Cit\u00e9 in Paris, investigated the most recently recorded signal (which was captured in January of 2007), they found that it was coming from somewhere far beneath the crust<\/a> or the ocean<\/a>.<\/p>\n GRACE used two satellites to detect gravitational anomalies from 2003 to 2015. Because one of the satellites orbits in front of the other, passing over a region with more mass meant more gravity that (since gravity increases with mass) would accelerate the satellite in the lead. If the lead satellite flew over an area with lower mass and gravity, it would slow down. Measuring the distance between the two helped create a gravitational map of the planet. When the gravity in a given area is stronger or weaker than what is expected, that is labeled a gravitational anomaly, and while they are relatively common, they have not been well understood.<\/p>\n Gouranton and her team found an anomaly that stood out after investigating GRACE data. Stretching 4,350 miles (7,000 km) over the eastern Atlantic, it persisted from 2006 through 2008, and manifested as an expanse of unusually strong gravity next to an area where gravity was weak. They initially thought that the ocean might be the source of the signal, but something was missing\u2014surface water alone could not completely explain the anomaly\u2019s intensity.<\/p>\n \u201cOur results suggest that this gravity signal originates deep within the Earth, near the base of the mantle,\u201d the researchers said in a study recently published in the journal Geophysical Research Letters<\/a>. \u201cWe propose that it may reflect rapid mass redistributions linked to a lower mantle mineral phase transition [\u2026], potentially causing dynamic changes in the core-mantle boundary’s shape over a few years.\u201d<\/p>\n At the core-mantle boundary<\/a> (CMB)\u2014the aptly-named interface between the mantle and core\u2014heat and pressure are so extreme that they can change the crystalline<\/a> structure of certain minerals<\/a>. Specifically, they can alter the mineral bridgmanite<\/a>, which crystallizes within the mineral perovskite<\/a>. Bridgmanite is the most abundant mineral on Earth, but it exists so deep in the mantle that it is far out of our reach, and could only be studied when it was found in a meteorite that fell to the surface.<\/p>\n It turns out that bridgmanite will undergo a phase transition<\/a> and morph into post-perovskite<\/a> if exposed to high enough temperatures and pressures. The density of post-perovskite is much lower than that of bridgmanite, and as a result, phase transitions like this affect the density in their region of the mantle. These then result in a redistribution of mass that shows up as a gravitational anomaly. Because the mantle is fluid and constantly changing, these anomalies are not permanent, and can show up anywhere in the CMB (where it becomes scorching and oppressive enough for a phase transition).<\/p>\n \u201cHow the obtained changes in CMB topography may influence core flow dynamics and the geomagnetic field is now to be investigated, as well as the existence of other such rapid events in the deep mantle during the GRACE(-FO) observation period and their modeling,\u201d Gouranton said<\/a>.<\/p>\n So, it turns out that gravitational anomalies strong enough to be detected from space begin right outside Earth\u2019s core. It really is that deep.<\/p>\n You Might Also Like<\/p>\n","protected":false},"excerpt":{"rendered":"Here\u2019s what you will learn when you read this story: Gravitational anomalies detected by NASA and the German…\n","protected":false},"author":2,"featured_media":186463,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[49,48,93653,93654,93649,93652,93651,93650,66],"class_list":["post-186462","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-ca","tag-canada","tag-crystalline-mineral","tag-earths-gravity","tag-german-aerospace-center","tag-gravitational-anomalies","tag-gravity-recovery-and-climate-experiment","tag-phase-transition","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/186462","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=186462"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/186462\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/186463"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=186462"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=186462"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=186462"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}