{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"546bdac8a16c1bcbbc3fa40a446bfbd758497fbeafd61270f2e2e2caeceb0bb5","created":"2026-10-03T07:18:03Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"54a313db8632b1a5d677d11405040a7f1d406bf3fd14a1bf990e0f1fbe3cb0f7","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"earth.venus-divergence.no-dynamo","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Venus has an iron core roughly as large as Earth's but no magnetic field of its own. Either its core does not churn today or something else stops a dynamo (a self-sustaining magnetic generator made by flowing liquid metal).","posed_since":"","precise":"Spacecraft limits put any intrinsic Venus dipole moment below roughly $1e-5$ of Earth's (approximate, from Pioneer Venus era data). Determine why the Venus core sustains no dynamo: low core-mantle heat flow under a stagnant lid with no inner-core growth, a fully liquid or fully solid core, or a compositionally stratified core formed without a late giant impact (Jacobson and coauthors, EPSL 2017, https://doi.org/10.1016/j.epsl.2017.06.023). An answer is a core state (radius, solid fraction, stratification) and core heat flow consistent with the measured tidal Love number $k_2$, the moment of inertia and a thermal history, including whether a dynamo operated in the past.","problem_ref":null,"references":"","settled_by":"Orbiter tracking that measures the Venus $k_{2}$ and moment of inertia precisely, combined with a search for remanent magnetization in old crust.","status_note":"","title":"Why does Venus have no internally generated magnetic field?","topic_ref":"2d563ce4d5d56d2365b73e28ad4b61c690ba87ce44cf2790d484e63faf665432"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"4c25e29e34f66825aeac161867c3d4f6dd377cf6326377be83cef182939c8a6d","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"1e949d2579d074c0159535f4d9df57cc014e41f70af22a476902a97c2ee1d365","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"66X-dCGcrFzQ7-yKl5FEQaE7l1YnFF5zbDV8It8rdGs3fMKQz0XrZpP0Xlc7a5Exwr_JcSWOyifhAci_2FR_Bg"},"schema":"pubphys.envelope/1"},"record_hash":"4c25e29e34f66825aeac161867c3d4f6dd377cf6326377be83cef182939c8a6d","leaf_index":1379}