Final answer:
It gets darker earlier in winter due to Earth's axis being tilted away from the Sun, leading to shorter days and longer nights, especially pronounced during the winter solstice. The distance from the Sun varies only slightly and is not the cause for the changing seasons.
Step-by-step explanation:
The reason it gets darker earlier in winter is due to the tilt of the Earth's axis. During winter in the Northern Hemisphere, the Earth is tilted away from the Sun, leading to shorter days and consequently, fewer hours of sunlight. It's a common misconception that the distance from the Sun dictates the seasons, but that variation is minimal (about 3%) and cannot be the cause of such significant temperature differences.
Additionally, during the winter solstice, which occurs around December 21, the Sun follows its shortest path through the sky which gives us the shortest day and longest night of the year. This is mirrored in the Southern Hemisphere where it's summer during this time, and they experience long days and short nights. The tilt of Earth's axis remains constant throughout its orbit, meaning that each hemisphere will alternatively lean towards or away from the Sun, leading to the changing seasons and the variation in day length.