Earthsky FAQs
Why aren’t the latest sunrises on the shortest day?
01-04-2010 - Earth
The winter solstice is the shortest day, but the latest sunrises come after the solstice, in early January. What’s more, the earliest sunsets come before the winter solstice.
This happens because as Earth spins on its axis to create day and night, it’s also orbiting the sun. In one day – one spin of the Earth – our motion in orbit causes the sun to shift a little, about a degree, eastward on our sky’s dome. So Earth has to spin a little extra toward the east each day to bring the sun up over your eastern horizon and for day to begin again.
The amount of extra spin varies over the course of a year because our distance from the sun changes over the year – and thus Earth’s speed in orbit changes. The effect is very pronounced near the winter solstice because we’re nearly closest to the sun and moving fastest in orbit.
The result: earlier sunsets before the solstice and increasingly later sunrises for a few weeks after the solstice.