USA Astronomy and Astrophysics Olympiad

The USA Astronomy and Astrophysics Olympiad (USAAAO) is a national competition for high school students in the United States of America. The competition consists of multiple rounds, including a First Round and the National Astronomy Championship (NAC). Top performers from USAAAO are invited to represent the United States at the International Olympiad on Astronomy and Astrophysics (IOAA). The competition tests knowledge and problem-solving skills in astronomy, astrophysics, and related fields.

2026 United States

Official Site

First Round 75 min → First Round Problems First Round Solutions NAC 150 min → NAC Problems NAC Solutions

Problem 1 (10 pts)

A "gravitational atom" NAC

Problem 2 (15 pts)

Celestial Sphere: Night at the Observatory NAC

Problem 3 (15 pts)

Sky Map Attack! NAC

Answer Sheet

Problem 4 (20 pts)

Solar Observatory NAC

Problem 5 (20 pts)

Enceladus Geysers NAC

Problem 6 (40 pts)

Build your Own H-R Diagram NAC

Answer Sheet

Problem 7 (40 pts)

Interstellar Flight NAC

Problem 8 (55 pts)

Watch Out! NAC

Problem 9 (85 pts)

Neutron Star Dynamics NAC

Answer Sheet

2025

First Round 75 min → First Round Problems First Round Solutions NAC 150 min → NAC Problems NAC Solutions

Problem 1 (15 pts)

Tracking a Bootes Planet NAC

Problem 2 (15 pts)

The Eye as a Camera NAC

Problem 3 (15 pts)

Sailing NAC

Problem 4 (20 pts)

Gravitational Waves NAC

Problem 5 (30 pts)

Stupendous Man's Saga NAC

Problem 6 (30 pts)

Spherical Cluster NAC

Problem 7 (55 pts)

Planetary Defense NAC

2024

First Round 75 min → First Round Problems First Round Solutions NAC 150 min → NAC Problems NAC Solutions

Problem S1 (15 pts)

The Boomerang Nebula NAC

Problem S2 (10 pts)

Gegenschein Dust NAC

Problem S3 (15 pts)

Stellar Dodecahedron NAC

Problem M1 (30 pts)

Solar Eclipse NAC

Problem M2 (25 pts)

Neutrino Decoupling NAC

Problem M3 (30 pts)

Spiff's Adventures NAC

Problem L1 (50 pts)

TESS NAC

Problem L2 (50 pts)

The Analemma NAC

2023

First Round 75 min → First Round Problems First Round Solutions NAC 150 min → NAC Problems NAC Solutions

Problem S1 (10 pts)

White Dwarfs NAC

Problem S2 (10 pts)

The Large Magellanic Cloud NAC

Problem S3 (15 pts)

Culmination Time NAC

Problem M1 (20 pts)

Hyperfine Splitting NAC

Problem M2 (20 pts)

Quantum Fusion NAC

Problem M3 (25 pts)

Into the Wilds NAC

Problem L1 (45 pts)

The Sundial II NAC

Problem L2 (40 pts)

Interstellar Comet NAC

Problem L3 (55 pts)

Finding Friends NAC

2022

First Round 75 min → First Round Problems First Round Solutions NAC 150 min → NAC Problems NAC Solutions

Problem S1 (10 pts)

Hydrogen Atom Energies NAC

Problem S2 (10 pts)

Binary Mass Function NAC

Problem S3 (10 pts)

Exoplanet Radius Transit NAC

Problem S4 (10 pts)

Posidonius Earth Measurement NAC

Problem S5 (10 pts)

Electron Orbital Energy NAC

Problem M1 (30 pts)

The Speed of Light NAC

Problem M2 (30 pts)

Meteorite Space Station NAC

Problem L1 (45 pts)

The Curious Orbit of James Webb NAC

Problem L2 (45 pts)

The Sundial I NAC

2021

First Round 75 min → First Round Problems First Round Solutions NAC 150 min → NAC Problems NAC Solutions

Problem S1 (5 pts)

Jupiter NAC

Problem S2 (5 pts)

Solar Interior NAC

Problem S3 (5 pts)

Seeing galaxies NAC

Problem S4 (5 pts)

Eccentric orbit NAC

Problem S5 (5 pts)

Winter sunset NAC

Problem M1 (20 pts)

Relativistic Clock NAC

Problem M2 (30 pts)

Hohmann Transfer NAC

Problem M3 (30 pts)

Space Station NAC

Problem L1 (40 pts)

Big Bang Nucleosynthesis NAC

Problem L2 (35 pts)

Conjunction NAC

2020

First Round 75 min → First Round Problems First Round Solutions NAC 150 min → NAC Problems NAC Solutions

Problem S1 (5 pts)

Quadrature NAC

Problem S2 (10 pts)

Betelgeuse NAC

Problem S3 (10 pts)

Lyman-Break NAC

Problem S4 (5 pts)

TRAPPIST-1d NAC

Problem S5 (5 pts)

HD 209458b NAC

Problem M1 (15 pts)

Telescoping a binary NAC

Problem M2 (20 pts)

Galaxy Rotation Curves NAC

Problem M3 (15 pts)

Moon NAC

Problem M4 (20 pts)

Black Holes NAC

Problem M5 (15 pts)

Stellar Properties NAC

Problem L1 (30 pts)

M15 Cluster NAC

Problem L2 (25 pts)

Sunspot Magnetograms NAC

2019

First Round 75 min → First Round Problems First Round Solutions NAC 150 min → NAC Problems NAC Solutions

Problem 1 (7 pts)

Nucleosynthesis NAC

Problem 2 (7 pts)

Lunar Eclipse NAC

Problem 3 (7 pts)

Seeing stars NAC

Problem 4 (7 pts)

Pressure Gradient NAC

Problem 5 (15 pts)

Terrestrial Precession NAC

Problem 6 (15 pts)

Exoplanet detection NAC

Problem 7 (15 pts)

Minimal Black Holes NAC

Problem 8 (15 pts)

A weird universe NAC

Problem 9 (15 pts)

Finding distances NAC

Problem 10 (25 pts)

Magnetic Moments NAC

Problem 11 (25 pts)

Cygnus X-1 NAC

2018

First Round 75 min → First Round Problems First Round Solutions NAC 150 min → NAC Problems NAC Solutions

Problem S1 (5 pts)

NAC

Problem S2 (5 pts)

NAC

Problem S3 (5 pts)

NAC

Problem S4 (5 pts)

NAC

Problem S5 (5 pts)

NAC

Problem S6 (5 pts)

NAC

Problem S7 (5 pts)

NAC

Problem S8 (5 pts)

NAC

Problem S9 (5 pts)

NAC

Problem S10 (5 pts)

NAC

Problem S11 (5 pts)

NAC

Problem L1 (15 pts)

WASP-14b NAC

Problem L2 (15 pts)

Sualocin and Rotanev NAC

Problem L3 (15 pts)

Fusing hydrogen NAC

2017

First Round 75 min → First Round Problems NAC 150 min → NAC Solutions

Problem 1 (5 pts)

NAC

Problem 2 (5 pts)

NAC

Problem 3 (5 pts)

NAC

Problem 4 (10 pts)

NAC

Problem 5 (10 pts)

NAC

Problem 6 (10 pts)

NAC

Problem 7 (15 pts)

NAC

Problem 8 (15 pts)

NAC

Problem 9 (15 pts)

NAC

2016

First Round 75 min → First Round Problems First Round Solutions NAC 150 min → NAC Problems

Problem 1 (6 pts)

NAC

Problem 2 (6 pts)

NAC

Problem 3 (6 pts)

NAC

Problem 4 (6 pts)

NAC

Problem 5 (6 pts)

NAC

Problem 6 (6 pts)

NAC

Problem 7 (6 pts)

NAC

Problem 8 (6 pts)

NAC

Problem 9 (6 pts)

NAC

Problem 10 (6 pts)

NAC

Problem 11 (6 pts)

NAC

Problem 12 (6 pts)

NAC

Problem L1 (30 pts)

NAC

Problem L2 (37 pts)

NAC

2015

First Round 75 min → First Round Problems First Round Solutions NAC 150 min → NAC Problems NAC Solutions

Problem 1 (2 pts)

NAC

Problem 2 (2 pts)

NAC

Problem 3 (2 pts)

NAC

Problem 4 (3 pts)

NAC

Problem 5 (3 pts)

NAC

Problem 6 (3 pts)

NAC

Problem 7 (3 pts)

NAC

Problem 8 (3 pts)

NAC

Problem 9 (3 pts)

NAC

Problem 10 (4 pts)

NAC

Problem 11 (4 pts)

NAC

Problem 12 (4 pts)

NAC

Problem 13 (6 pts)

NAC

Problem L1 (25 pts)

NAC

2014

NAC 150 min → NAC Problems NAC Solutions