Historical clue formulations

• Capital of São Tomé and Príncipe — 2023-04-01
• Island just north of the Equator — 2018-08-24
• Príncipe's sister island — 2017-07-17
• Island off the Gabonese coast — 2013-05-02
• Portuguese-speaking island off the African coast — 2010-11-21
• Island just north of the Equator — 2007-09-08
• It's just north of the equator — 2002-07-27