Can you catch the Sun with stones?

That time, that place

Southern Britain around 2500 BC — no writing, no metal tools. People farmed, and farming begins with knowing the season. But without a calendar, how do you know?

Why this question

The Sun rises a little further along the horizon each day — north toward summer, south toward winter — until one day it stops and turns back. Catch that turning day and you have the year's hinge. The problem is how to remember it.

What was found

Instead of paper, they used the ground. They raised enormous stones to mark the direction of the Sun on its turning day. Stonehenge's main axis lines up with midsummer sunrise — and, looking the other way, midwinter sunset. A marker weighing tens of tons.