BAAO — British Astronomy and Astrophysics Olympiad
The UK national olympiad in astronomy and astrophysics, administered by the British Physics Olympiad trust. It selects and trains the British team for the IOAA through tiered papers and an Oxford selection camp.
- Founded
- 2015
- Host rotation
- National (United Kingdom), run by the British Physics Olympiad trust
- Level
- National (United Kingdom)
- Format
- Written papers of increasing difficulty plus a residential selection camp
- Rounds
- Astro Challenge (Year 10 and below), Astro Round 1, Astro Round 2, selection camp in Oxford
- Eligibility
- UK secondary-school students in Year 13 and below (papers graded by year group)
- Website
- www.bpho.org.uk/baao
Notable facts
A relatively young competition within the BPhO family. Its hardest papers deliberately stretch beyond school physics, rewarding students who self-study astrophysics.
Recent editions
| Year | Host |
|---|---|
| 2025 | Oxford (selection camp) |
| 2024 | Oxford (selection camp) |
Typical topics
Past problems
2024
Hohmann transfer to Mars
A probe departs Earth's orbit for Mars along a minimum-energy Hohmann ellipse. Assuming circular coplanar orbits at 1.0 and 1.52 AU, compute the transfer time and the heliocentric speed required at departure, then find how far Mars advances along its orbit during the cruise.
Show solution
The Hohmann ellipse has semi-major axis a = (1.0 + 1.52)/2 = 1.26 AU. The transfer time is half its period: t = 0.5·(1.26)^1.5 yr ≈ 0.71 yr ≈ 259 d. Vis-viva at departure gives v = sqrt(GM_sun(2/r_E − 1/a)) = sqrt(GM_sun(2/1.0 − 1/1.26)) ≈ 32.7 km/s, i.e. a departure Δv ≈ 2.9 km/s above Earth's 29.8 km/s. During the 259 d cruise Mars advances 360° × 259/687 ≈ 136° along its orbit, so it must be ~44° ahead of Earth at departure.