Date: 2 Jun 2026
Topic: Science
Codebreakers are a fun way to build numeracy skills.
Troposphere (0–12 km) - Contains ~75% of the atmosphere's mass and almost all weather. Commercial aircraft fly near the top of this layer.
Stratosphere (12–50 km) - Contains the ozone layer, which absorbs most harmful UV radiation from the Sun.
Mesosphere (50–85 km) - Coldest atmospheric layer. Most meteors burn up here due to friction with the air.
Thermosphere (85–600 km) - Contains the auroras and the International Space Station (~400 km). Temperatures can exceed 1,500°C.
Kármán Line (100 km) - The commonly accepted boundary between Earth's atmosphere and outer space. Rockets travel around 2km/s when they cross this boundary into outer space.
Exosphere (600–10,000 km) - Air is so thin that particles can travel hundreds of kilometres without colliding.
Low Earth Orbit (160–2,000 km) - Home to the ISS, Starlink satellites, and many Earth observation satellites.
Medium Earth Orbit (2,000–35,786 km) - Home to GPS, Galileo, and other navigation satellites.
Geostationary Orbit (35,786 km) - Satellites orbit once every 24 hours, appearing stationary above the same point on Earth.
Moon (384,400 km) - Light takes about 1.3 seconds to travel from the Moon to Earth, or 3 days in a space shuttle.