The sun is lower in the sky on the December solstice because of the tilt of the Earth's axis. During this time, the Northern Hemisphere is tilted away from the sun, causing the sunlight to hit the Earth at a lower angle. This results in shorter days and longer nights in the Northern Hemisphere during the December solstice. Conversely, the Southern Hemisphere experiences their summer solstice during this time, with longer days and shorter nights as they are tilted towards the sun.
