Today is the December Solstice, the first day of winter in the northern hemisphere. The new season officially began this morning at 6:12 AM Eastern Standard Time.
Seasons are the result of the tilt of the Earth’s axis, a 23.5° angle. Today, as winter begins, the northern half of the Earth is tilted away from the sun. This position brings the northern hemisphere the least amount of solar energy all year.
Today is also the shortest day of the year. Since the summer solstice in June, the sun – in its apparent seasonal journey across the sky – has been making its way south. Today, it reached its southern most position at the Tropic of Capricorn. Now, the sun will begin to move northward again and our daylight hours will slowly start to increase.
Marking the transition to longer days, the winter solstice has been a cause for celebration across many cultures throughout human history.