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Under the extreme pressures found deep inside super-Earths, molten mantle material has been observed to become electrically conductive in ways that can power planetary magnetism.<\/p>\n
Miki Nakajima and colleagues at the University of Rochester<\/a> document this behavior by showing that compressed mantle melt can sustain electric currents under interior planetary conditions.<\/p>\n Her research focuses on violent planet formation and the hidden layers that decide whether atmospheres survive long enough for chemistry.<\/p>\n New results tie that survival to magnetic fields generated within layers of deep molten rock.<\/p>\n Why magnetic shields matter<\/p>\n Life on land depends on a magnetosphere<\/a>, a magnetic bubble that steers charged particles away from the surface.<\/p>\n On Earth, swirling liquid iron in the outer core generates currents, and those currents build the global magnetic field.<\/p>\n When stars release charged gas and high-energy particles, magnetic fields can steer much of that material away.<\/p>\n Many rocky planets appear to lose that protection, so magnetism has become a key habitability checkpoint for astronomers.<\/p>\n Bigger planets break old rules<\/p>\n Astronomers keep finding super-Earths<\/a> \u2013 planets more massive than Earth yet lighter than Neptune \u2013 around other stars.<\/p>\n Their extra mass squeezes interiors hard, changing how iron and rock behave and sometimes leaving a core that stops stirring.<\/p>\n A planet can have a solid core too stiff to flow, or a fully liquid one without the right layering.<\/p>\n Either way, the classic iron-core engine for magnetism can fade, even while the surface still looks rocky.<\/p>\n A second magnetic engine<\/p>\n Early Earth likely carried a deep molten layer, and larger rocky planets may keep it long after surfaces harden.<\/p>\n Researchers call this layer a basal magma ocean<\/a>, a melt zone resting at the mantle\u2019s bottom.<\/p>\n If the melt conducts electricity, its slow circulation can drive a dynamo<\/a>, the process that converts fluid motion into a magnetic field.<\/p>\n That idea changes the habitability math, because a magnetic field might survive even when an iron core cannot.<\/p>\n Rebuilding alien pressures here<\/p>\n At URochester\u2019s Laboratory for Laser Energetics, pulses hit targets and launched shock waves<\/a> \u2013 pressure fronts that squeeze materials fast.<\/p>\n \u201cThis work was exciting and challenging, given that my background is primarily computational and this was my first experimental work,\u201d said Nakajima.<\/p>\n Those brief tests then informed computer models that estimated whether the same melt could remain active for billions of years.<\/p>\n Under crushing pressure, molten rock that normally blocks electric current began to carry it, behaving as a conductor rather than an insulator.<\/p>\n The pressure pushed atoms closer together, allowing electrons to move more freely and lose less energy.<\/p>\n At deep pressures, magnesium oxide and lightly iron-tinted versions showed similar conductivity<\/a>. In both cases, the molten material could carry electric current.<\/p>\n That result undercut earlier expectations that iron would boost current flow by orders of magnitude in the deepest melt.<\/p>\n Scale makes shields last<\/p>\n Planet size mattered because thick mantles hold heat and keep the deep melt moving for much longer.<\/p>\n As a world grows, convection spans a larger distance, and faster flow strengthens the magnetic feedback that keeps fields stable.<\/p>\n Models suggested planets above three to six times Earth\u2019s mass could sustain magma-driven fields almost ten times stronger for several billion years.<\/p>\n Even then, a strong field was not guaranteed as cooling rates and internal composition determine whether the melt keeps moving.<\/p>\n Finding fields from far<\/p>\n Magnetic fields do not show up directly in most telescope images, so researchers hunt for indirect signs.<\/p>\n One approach<\/a> looks for radio emission produced by aurora-like activity when stellar particles collide with a magnetized planet.<\/p>\n Another path tracks how stellar outbursts disturb a planet\u2019s upper atmosphere, since magnetic defenses can change the timing and pattern.<\/p>\n Even promising signals can have other causes, so a magnetic field claim usually needs several lines of evidence.<\/p>\n Why magnetism is not enough<\/p>\n Habitability still depended on many details, from a star\u2019s flare behavior to whether a planet can keep water and air.<\/p>\n \u201cA strong magnetic field is very important for life on a planet,\u201d said Nakajima.<\/p>\n A deep-melt dynamo could help by lowering atmospheric erosion, because fewer charged particles reach the upper air with enough speed.<\/p>\n Yet a field alone could not guarantee habitable ground, since temperature, chemistry, and time also set the limits for biology.<\/p>\n By linking deep molten rock to long-lived magnetism, the work expanded the range of rocky planets considered promising for habitability studies.<\/p>\n If upcoming observations can spot these fields, researchers will better judge which super-Earths hold atmospheres steady for billions of years.<\/p>\n The study is published in the journal Nature Astronomy<\/a>.<\/p>\n Photo credit: University of Rochester Laboratory for Laser Energetics illustration \/ Michael Franchot<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Deep layers of molten rock inside large rocky planets have been shown to generate magnetic fields strong enough…\n","protected":false},"author":2,"featured_media":315668,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[77],"tags":[18,19,17,133],"class_list":{"0":"post-315667","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-eire","9":"tag-ie","10":"tag-ireland","11":"tag-science"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ie\/115998165767937463","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/315667","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=315667"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/315667\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/315668"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=315667"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=315667"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=315667"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}