<p>The Singapore Astronomy Olympiad (SAO) is Singapore's national olympiad in astronomy and astrophysics. The top five Gold medalists represent Singapore at the International Olympiad on Astronomy and Astrophysics (IOAA); the 19th IOAA is hosted in Hanoi, Vietnam from 25 September to 5 October 2026.</p><ul><li>Open to students under 20 as of 1 July who have not exceeded Grade 12 or equivalent</li><li>Round 1 (open entry) is a 2-hour computerised multiple-choice test, taken in schools or at a centralised facility</li><li>Round 2 (by invitation) is a 4-hour paper covering short and long-answer questions, data analysis, and practical or observational astronomy</li><li>Only Singapore citizens and permanent residents are eligible to represent Singapore at the IOAA</li><li>Past papers, the IOAA syllabus, and additional preparation material are published on the Astronomy.SG site</li></ul><p>Registration and announcements are issued via the Astronomy.SG website; queries go to the organising team via the contact page.</p>