Polar motion dynamics on the slow-rotating Venus: signatures of mantle flow

Polar motion dynamics on the slow-rotating Venus: signatures of mantle flow | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Polar motion dynamics on the slow-rotating Venus: signatures of mantle flow Vojtěch Patočka, Julia Maia, Ana-Catalina Plesa This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6841068/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract With one day lasting 243 days on Earth, Venus is the slowest‐spinning planet in the Solar System and its rotational bulge is anomalously small. Without the bulge as stabilizer, rotational pole has been expected to separate from figure pole in response to mantle flow, which has been used to explain the observed 0.5° offset between Venus’ spin and figure axes. Here, we couple 3D mantle‐convection simulations and polar motion dynamics to explore how mantle flow, and in particular surface mobilization, drives Venus’s polar motion. We provide a predictive framework for polar motion on slow rotators and show that the angular offset follows a simple law: it scales with the figure‐axis drift rate times the planet’s Chandler period. Contrary to prior expectations, stronger internal loading does not amplify the offset and the mantle‐driven polar motion is smooth rather than wobbly, more similar to fast rotators. In models matching Venus’s geoid, figure‐axis drift rates reach only a few °/Myr, too slow compared to ca. 60°/Myr that is needed to produce the observed 0.5° offset. We therefore exclude mantle convection as the cause of Venus' spin and figure poles separation, and implicate that atmospheric and solar torques are not balanced instead. Earth and environmental sciences/Planetary science/Geodynamics Earth and environmental sciences/Planetary science/Atmospheric dynamics Physical sciences/Astronomy and planetary science/Astronomy and astrophysics/Computational astrophysics Physical sciences/Physics/Fluid dynamics Venus Polar motion Chandler wobble Mantle convection Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6841068","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":481720001,"identity":"56461e26-6719-438a-a902-39c40d69e0b8","order_by":0,"name":"Vojtěch Patočka","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABDElEQVRIiWNgGAWjYNCCA2AyAcSSA/Mf4FXODNeS2ABkGYO1JBCphRGkBaQPYiEuYM5+/uCDH2fsGAyONzx/8KHmTvr8sMMPgbbYyek2YNdi2ZPMbNhzI5nB4MyBxMYZx57lbrydZgDUkmxsdgC7FoMDyWzSDB+YGSRnJCQ28zYczt04OwGk5UDiNlxazj8GaamHaPnbcDjdcHb6B/xaboBsuXGYgV8CqIWx4XCCvHQOflssZzw2Nuw5c5yHn+dA4syeY4cNN0jnFBxIMMDtF3P+xIcPfhyrlmNj70n48KPmsLz87PTNHz5U2Mnh9D6U5gGiBGiAIIvj0QIE7BBT5Rtwqx4Fo2AUjIKRCQA+aGpMwP+yagAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-3413-6120","institution":"Charles University in Prague","correspondingAuthor":true,"prefix":"","firstName":"Vojtěch","middleName":"","lastName":"Patočka","suffix":""},{"id":481720002,"identity":"c7d7e160-6be1-46cc-a7b8-1d03363ce1c8","order_by":1,"name":"Julia Maia","email":"","orcid":"","institution":"German Aerospace Center, DLR","correspondingAuthor":false,"prefix":"","firstName":"Julia","middleName":"","lastName":"Maia","suffix":""},{"id":481720003,"identity":"8083345c-ebb6-421a-b4f8-77518e272a31","order_by":2,"name":"Ana-Catalina Plesa","email":"","orcid":"https://orcid.org/0000-0003-3366-7621","institution":"German Aerospace Center (DLR)","correspondingAuthor":false,"prefix":"","firstName":"Ana-Catalina","middleName":"","lastName":"Plesa","suffix":""}],"badges":[],"createdAt":"2025-06-07 07:00:33","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6841068/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6841068/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":86224682,"identity":"f8631fa7-5844-4b73-beec-114466d09b60","added_by":"auto","created_at":"2025-07-08 07:53:22","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3183150,"visible":true,"origin":"","legend":"Article File","description":"","filename":"NGSemailattachmentSMC17495060911.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6841068/v1_covered_5562ceb7-d9c4-41a6-bd31-1d35f853f333.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Polar motion dynamics on the slow-rotating Venus: signatures of mantle flow","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Venus, Polar motion, Chandler wobble, Mantle convection","lastPublishedDoi":"10.21203/rs.3.rs-6841068/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6841068/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"With one day lasting 243 days on Earth, Venus is the slowest‐spinning planet in the Solar System and its rotational bulge is anomalously small. Without the bulge as stabilizer, rotational pole has been expected to separate from figure pole in response to mantle flow, which has been used to explain the observed 0.5° offset between Venus’ spin and figure axes. Here, we couple 3D mantle‐convection simulations and polar motion dynamics to explore how mantle flow, and in particular surface mobilization, drives Venus’s polar motion. We provide a predictive framework for polar motion on slow rotators and show that the angular offset follows a simple law: it scales with the figure‐axis drift rate times the planet’s Chandler period. Contrary to prior expectations, stronger internal loading does not amplify the offset and the mantle‐driven polar motion is smooth rather than wobbly, more similar to fast rotators. In models matching Venus’s geoid, figure‐axis drift rates reach only a few °/Myr, too slow compared to ca. 60°/Myr that is needed to produce the observed 0.5° offset. 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