{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"993ea71f8e5b01edbe748338603bd60c723453b248727a120896091283f55140","created":"2026-10-03T07:17:55Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"d3d320f9df2a0e73647a5d585f8697248fffa627874e9212488b7bd3abcee274","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"astro.radius-valley.radius-cliff","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"Planets just under three Earth radii are very common, but slightly larger ones are much rarer. Something must stop envelopes from growing, possibly hydrogen dissolving into molten rock.","posed_since":"","precise":"The occurrence rate of close-in planets falls by about an order of magnitude between $R_{p} \\sim 3$ and $\\sim 4\\ R_{\\mathrm{earth}}$. Identify the mechanism: hydrogen sequestration into magma oceans that limits envelope growth, runaway gas accretion that depletes the intermediate range, or a formation-mass cutoff, and predict how the cliff location depends on stellar mass and instellation.","problem_ref":null,"references":"","settled_by":"Cliff location versus host and orbit properties compared with interior-atmosphere evolution models including hydrogen solubility.","status_note":"","title":"Why do planet numbers drop steeply above three Earth radii?","topic_ref":"29eecacca9d688759063e837d47b7481ed1a91ff74dcb512159e65510cf6039a"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"56710e1ee2d6a02a4a2e80b517b7c611d291c50ae296cbc63c0274fc713c7264","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"1ac5a0b3a46b5e6b8a68a7cb765564e65c2986661182534c83d86d54b4926c18","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"9UMJYQQnKKAnjYo0QRazMoT-7NhGhJUNtKnB5W5flpZWkcoSEyTBkjfQ4HCGkbNaO56Tt3geknckJ_YLFhuyCQ"},"schema":"pubphys.envelope/1"},"record_hash":"56710e1ee2d6a02a4a2e80b517b7c611d291c50ae296cbc63c0274fc713c7264","leaf_index":598}