The International Olympiad on Astronomy and Astrophysics for Juniors (IOAA-jr) is the junior branch of the IOAA. It runs once a year for students in the early years of secondary school, and its stated aim is to introduce them to astronomy and astrophysics and put them alongside peers from other countries.
The fifth edition runs from 1 to 8 November 2026 in Ubon Ratchathani, Thailand. It is hosted jointly by the Promotion of Academic Olympiad and Development of Science Education Foundation (POSN), Ubon Ratchathani Province, Ubon Ratchathani University and the National Astronomical Research Institute of Thailand, with support from Thailand’s education and higher-education ministries.
Countries take part as national delegations. A student reaches the olympiad by being selected onto a national team by the olympiad committee in their own country; IOAA tells students in countries without such a committee to ask their teachers about forming one.
Benefits & funding
- A place at an eight-day international olympiad, with the opening ceremony on 2 November 2026 and the closing ceremony on 8 November 2026.
- Gold, silver and bronze medals plus honourable mentions, with separate prizes for best theory, best observation, best blind map, best overall performance and the group competition.
- No prize money and no scholarship. Delegations pay to attend: under the IOAA-jr regulations a host may charge a regular team member up to EUR 500 per person, and a guest-team member or observer up to EUR 1,000 per person.
- The 2026 host publishes an invoicing window and a payment window but does not publish the fee amount.
- The regulations cap what a host may charge. They do not say whether the student or the sending committee bears the cost.
Eligibility
- Secondary-school students who are at most sixteen years old on 30 June of the competition year. For the 2026 edition that means born on or after 1 July 2010. The 2026 host page describes the audience more loosely as junior high school students under 16.
- Contestants must be two or more years away from completing high school at the time of the competition.
- No nationality is excluded. Entry runs through national teams, so a student’s country has to register one; the 2026 pre-registration round was capped at 30 countries for main teams.
- A regular national team is 2 to 5 contestants with 1 or 2 team leaders. A host may also admit a second team from a country as a guest team, and additional accompanying adults as observers.
- Students cannot enter directly. IOAA directs them to the national olympiad committee in their own country.
Can you apply?
Here's who can apply
Decoded from the official rules. A free account checks them against your passport, degree and age in seconds.
Education required
High School
Age requirement
≤ 16 yrs
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Application process
- 1Check whether your country already sends a team, then contact its national olympiad committee.
- 2Sit that committee’s national selection round. It decides who joins the national team.
- 3The committee pre-registers the country with the host (10 February to 20 March 2026 for the 2026 edition).
- 4The committee files the main registration with the names of contestants and team leaders (20 April to 30 June 2026).
- 5The host verifies the data and issues an invoice (1 to 15 July 2026), and the delegation pays inside the payment window (15 July to 30 August 2026).
- 6The delegation travels to Ubon Ratchathani for the olympiad, 1 to 8 November 2026.
Program timeline
Pre-registration opens
Feb 10, 2026
Pre-registration closes
Mar 20, 2026
Main registration opens
Apr 20, 2026
Main registration closes
Jun 30, 2026
Data verification and invoicing
Jul 1, 2026 to Jul 15, 2026
Payment period
Jul 15, 2026 to Aug 30, 2026
5th IOAA-jr begins in Ubon Ratchathani
Nov 1, 2026
Opening ceremony
Nov 2, 2026
Closing ceremony and awards; olympiad ends
Nov 8, 2026