Stonehenge
Major effort involved
- No wheels, carts, trucks, etc. to help move stones
- Huge stones ~ 20 ft. high
- Rocks came from coast of Wales -- drug 50 miles!
At least one alignment looks very astronomical
- From center of monument to “heelstone” f. 4-1
- aligned with rising sun at Summer Solstice
- knowledge of seasons very important
- when to plant, harvest crops
- when to get warm clothing and supplies together for winter
- period of seasons 365.25 d, can’t just count days!
- great distance to heelstone (70 m) leads to accurate determination
- small angle formula, naturally
- example: 1 ft. rock 10 and 100 ft. distant