Day, seasons and Moon phases sim
Drag a classroom tellurion's arm round its lamp, spin its tilted globe and turn its Moon, predict the season and the Moon's phase before they are shown, work out the noon Sun's height in Singapore and London and graph the day length through the year.
The Earth: day and night, the seasons, the Moon's phases · covers the IGCSE topic
What the sim shows
Model: the Earth goes round the Sun in 365.25 days on a circle, spins once in 24 hours, and its axis is tilted 23.4° and always leans the same way; the Sun is overhead at noon at δ = asin(sin 23.4° × the share of the tilt toward the Sun); noon height 90° − |latitude − δ|; day length from cos H = −tan(latitude) × tan δ. The Moon's phase repeats every 29.5 days; the lit share seen from Earth is (1 − cos E) ÷ 2. Not to scale; flat Moon orbit; parallel sunlight; values from memory. Nothing runs on its own.
- The globe: the Earth, on an axis tilted 23.4° that always leans the same way
- A classroom tellurion: the lamp is the Sun; the Moon rides on its own arm
Use it in your lessons
- Try it here: anyone can unlock 2 figures free, and a free account unlocks up to 5. Runs on a laptop, a Chromebook or a phone; nothing to install.
- Present it and share student links with the teacher plan, from US$5 a month, billed yearly.
- Put it on your own website or LMS for US$9, paid once, or every sim from US$29 a month.
Free guide: 12 practicals as sims, and how to run one in a lesson →
Need a version for your exact set-up? Have one made: US$49 a figure in an order of 5.
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