🔄 Seasons as a time cycle

A year is defined by how long it takes Earth to travel the entire loop around the sun and return to the exact same starting point, which happens to take about three hundred and sixty five days. Nothing about that length is random, it comes straight from how big Earth's orbit is and how fast our planet moves through space. Every calendar, no matter which culture created it, is really just a different way of dividing up that same one trip around the sun.

Instead of tracking all three hundred and sixty five days one by one, many calendars split the year into four roughly equal chunks of time, called seasons, each lasting about three months. This makes the year much easier to think about, since you can plan around an entire season instead of counting individual days. The four seasons always happen in the exact same order, over and over, which is part of what makes a year feel like a steady, repeating cycle rather than a random stretch of time.

A solstice is the single day each year with either the most daylight hours or the fewest, marking the moment the length of daylight stops growing and starts shrinking, or the other way around. An equinox is a different kind of marker, a day when daylight and darkness last almost exactly the same number of hours, splitting evenly right down the middle. Together, these four points in the year act like signposts that mark the start of each new season on the calendar.

Calendars mark the solstices and equinoxes on specific, fixed dates each year, giving every season an official start and end date that stays roughly the same year after year. Because these dates come from Earth's orbit around the sun rather than from anything humans invented, they land on almost the same day every single year, with only tiny shifts. This is exactly why a calendar can tell you months in advance exactly which day a new season will officially begin.