Henge
river.io llc Education iPhoneiPadiPod touch
Henge is a free Education app for iPhone and iPad by river.io llc. Requires iOS 17.0. Updated September 16, 2026.
- Price
- Free
- on the App Store
- Size
- 11 MB
- Age 4+
- Updated
- Sep 16
- 2026 · v0.2.1
Screenshots
About Henge
THE MONUMENT • The whole circle raised: thirty sarsen uprights and their lintel ring, the five great trilithons, the bluestone circle and horseshoe, the Altar, Slaughter and Heel Stones, the Station Stone rectangle and the fifty-six Aubrey holes — every stone carrying its Petrie number. • On real ground: the terrain is Salisbury Plain's own survey data, and the ridge the midsummer sun clears is the one that actually stands there. • Weathered sarsen and Preseli bluestone, damp courses and lichen, wind moving through the grass, torchlight for the dark hours. THE CALENDAR • The Wheel of the Year: solstices, equinoxes and the four cross-quarter festivals — Imbolc, Beltane, Lughnasadh, Samhain — each landing on the instant the sun actually arrives, not on a calendar date. • Moon phases, eclipse seasons and the 18.6-year lunar standstill, solved from the real ephemeris. • A time machine from 3000 BC to AD 3000. Watch Thuban hold the celestial pole for the builders in an age when Polaris was no use to anyone. • The sky over your own longitude, or over Wiltshire. HONEST ARCHAEOLOGY Every claim the app makes about the monument carries its tier — Established, Debated, or Modern tradition — with the sources one tap away. The solstice axis is established. The equinoxes at Stonehenge are modern tradition, and the app says so. Free to explore in fifteen-minute sessions. One purchase unlocks the clock and the calendar for good — no subscription, no account, no network, and no data collected.
What’s new
Version 0.2.1 · Updated September 16, 2026
The sunrise bearing is corrected. Refraction used the wrong formula, and the skyline came from radar that counted tree tops as ground; the two errors hid each other and put the midsummer sun half a degree north of where it rises. The terrain is now bare-earth LiDAR from the Environment Agency, checked against a photographic panorama taken inside the circle. The Milky Way, from NASA's map of the Gaia sky, turning with the stars and precessing with them. A zodiac-only sky: a new switch keeps the stars of the twelve zodiac figures and the planets, and puts the rest out. Faster. The scene is drawn at 0.7 scale and lifted by MetalFX, the grass thins with distance, and the shadow maps are redrawn only when something moves — about 60% more frames a second at the sunrise on iPad Pro. With thanks to Simon Banton and David Hoyle for the skyline check.
App privacy
The developer, river.io llc, reported these privacy practices to Apple.
Data Not Collected
The developer does not collect any data from this app.
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| App | Rating | Price | Last updated | Compare |
|---|---|---|---|---|
| Henge | – | Free | September 16, 2026 | |
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