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Both planets sit far beyond Saturn, yet what they are actually made of remains surprisingly uncertain, even after Voyager 2 flew past.<\/p>\n
Classifying Uranus and Neptune<\/p>\n
The work was led by Luca Morf, a doctoral student at the University of Zurich (UZH<\/a>) who specializes in giant planet interiors.<\/p>\n His research focuses on building agnostic models, computer generated interior structures that make as few assumptions as possible about what lies inside.<\/p>\n For decades Uranus and Neptune have been grouped as ice giants, planets whose interiors<\/a> should be dominated by water, methane, and ammonia. <\/p>\n Standard models place most of their mass in a hot dense fluid of ices above a small rocky core.<\/p>\n The new study asks whether those same observations could also match planets where rock contributes much more of the total mass than usual.<\/p>\n Planets that are poorly understood <\/p>\n Earlier interior studies often used physical models that enforced a single density, temperature, and composition profile for each planet.<\/p>\n Other teams relied on empirical fits that matched spacecraft data but sometimes produced interiors with unrealistic temperatures or sharp density jumps.<\/p>\n \u201cThe ice giant classification is oversimplified as Uranus and Neptune are still poorly understood,\u201d said Morf.<\/p>\n His team wanted models flexible enough to include many possible rock and water combinations yet strict enough to obey known physics.<\/p>\n How planets are modeled<\/p>\n The new framework begins with a randomly generated density profile from the center of the planet to its outer atmosphere.<\/p>\n From that profile, the team computes the planet\u2019s gravity field and gravitational moments<\/a>, numbers that describe how mass varies with depth.<\/p>\n They then adjust mixtures of hydrogen, helium, water, rock, and iron using an equation of state<\/a>, which links pressure, temperature, and density.<\/p>\n Each time the algorithm cycles, it nudges density and pressure toward values that respect hydrostatic balance while matching the observed gravity data.<\/p>\n Rock hidden under icy layers<\/p>\n In their new study, Morf and Ravit Helled show that Uranus can have rock to water ratios between 0.04 and 3.92.<\/p>\n Their Neptune models span ratios from 0.20 to 1.78, ranging from water-dominated interiors to ones strongly dominated by rock.<\/p>\n Those numbers include classic water-rich cases and more extreme options where rock supplies most of the interior mass.<\/p>\n The same flexible approach can accommodate very different mixtures of rock and volatile material without forcing everything into a single preferred interior blueprint.<\/p>\n Taken together, these results suggest large outer solar system planets may hide rock-heavy interiors under layers that only look icy from afar.<\/p>\n Strange magnetic clues<\/p>\n Voyager 2 revealed that Uranus and Neptune have lopsided multipolar magnetic fields rather than the simple two pole pattern seen on Earth.<\/p>\n \u201cOur models have so-called \u201cionic water\u201d layers which generate magnetic dynamos in locations that explain the observed non-dipolar magnetic fields,\u201d said Helled.<\/p>\n Ionic water<\/a>, high-pressure water where molecules break into charged particles, conducts electricity strongly and can drive a magnetic field when it moves.<\/p>\n Earlier calculations<\/a> linked ionic or even superionic water to the unusual magnetic fields of Uranus and Neptune.<\/p>\n The new models place those conducting layers at depths consistent with that earlier scenario overall.<\/p>\n What other worlds teach us<\/p>\n Measurements of Pluto\u2019s bulk density indicate that roughly two-thirds of its mass is rocky, with the rest mainly composed of water ice.<\/p>\n A rock-rich interior beneath bright surface ice suggests that large, cold bodies do not always fit simple labels.<\/p>\n Sub-Neptune<\/a> planets, worlds between Earth and Neptune in size, are now a standard category in exoplanet surveys.<\/p>\n They also appear to be the most common planets around Sun-like stars in current catalogs<\/a>. Understanding Uranus and Neptune in detail could anchor interpretations of hundreds of distant planets with similar masses and radii.<\/p>\n Working with limited data <\/p>\n Even with the new algorithm, the biggest unknown is how mixtures of water, rock, and other materials behave under deep interior pressures.<\/p>\n Small uncertainties in high-pressure equations of state can change inferred densities by several percent, yielding different totals for rock, water, and gas.<\/p>\n Gravity measurements for Uranus and Neptune mostly come from brief Voyager 2 flybys, leaving only limited constraints on how mass is layered inside.<\/p>\n Because many interior structures can reproduce the same mass, radius, and gravity field, the authors argue that no single model should be final.<\/p>\n Future missions to Uranus and Neptune<\/p>\n To learn whether these planets are rock dominated, water dominated, or something between, scientists need better data than one flyby.<\/p>\n \u201cBoth Uranus and Neptune could be rock giants or ice giants depending on the model assumptions,\u201d said Helled, the study\u2019s principal investigator.<\/p>\n Orbiters could map their gravity and magnetic fields, while atmospheric probes would sample composition, winds, and heat flow at greater depths.<\/p>\n Such missions would resolve arguments about the two blue worlds and sharpen the tools used to interpret ice-rich exoplanets across our galaxy.<\/p>\n The study is published in Astronomy & Astrophysics<\/a>.<\/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":"New computer models of Uranus and Neptune suggest these distant worlds might be rock giants rather than pure…\n","protected":false},"author":2,"featured_media":185321,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[85,46,141,145],"class_list":{"0":"post-185320","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-space","8":"tag-il","9":"tag-israel","10":"tag-science","11":"tag-space"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/185320","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/comments?post=185320"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/185320\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media\/185321"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media?parent=185320"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/categories?post=185320"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/tags?post=185320"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}