We get our Northern Hemisphere winter and summer from the wobbling of the earth on its axis, the tilting of the earth's halves toward and away from the sun. The moments when the tilt shifts back the opposite direction have always carried heavy significance for the human race. The exact measurement of those moments is why Stonehenge was built. It's why the celebration of Jesus' birth got placed on the old Roman calendar at the Winter Solstice.
The Northern Hemisphere reached its maximum tilt toward the sun this morning at 7:28 a.m. At 7:29 it had begun to tilt back toward what will ultimately give us (dare we say it?) ... winter.
I was in my garden at 7:28 to feel the earth move.
Now I'm going to go plant a tree.