The reason we have seasons is because, during its journey around the Sun, the Earth is tilted.
If we didn't correct for gravitational effects on the Earth's orbit, the winter solstice would shift backwards by a day every 72 years.
For indigenous peoples, winter solstice has been a time to honor their ancient sun deity. Their rituals reveal a deep understanding of the natural world.
At many Spanish missions in the US and Latin America, the rising sun illuminates the altar on the winter solstice or other symbolic days. To the faithful, these events meant that Christ was with them.