Florals for spring. Groundbreaking. It's the seasons episode of Hello from the Van. Ah yes, the seasons. Spring, summer, fall, and winter. Who determines those? You see, this last week my kids went through an existential crisis. An existential crisis is when you question something that you previously believed to be true. They asked me what time it was, and I jokingly said, does it matter? Time's made up anyway. Now, me stating that time was made up, well, that got my kids questioning everything. And that was just a little too much for a regular old Tuesday. But that's a topic for another podcast because today we're talking about their very natural follow-up question. Who determines the seasons? Is that made up too? And this led me down a research rabbit hole, and today I'm taking you with me. To start, we need to lay some groundwork and to be very specific in what we're talking about. We are talking about the dates of the first day of spring, the first day of summer, the first day of winter. Who determines those dates? While this week's questions may seem based in culture and in history, their answers actually lie in science. Specifically the solar system and the tilt of the earth. Let me explain. A lot of people think that the earth is closest to the sun in summer and farthest away in winter. That's not actually true. Yeah, it makes a lot of sense. Like, oh yeah, close to the sun, warm, hot, ooh, summer. Yeah, nope, wrong, wrong, incorrect, not factual. Big ol' thumbs down to that. It is not correct at all. Here's what NASA has to say. Quote: In the northern hemisphere, it is the opposite. We have winter when Earth is closest to the sun, and summer when it is farthest away. Compared with how far away the sun is, this change in Earth's distance throughout the year does not make much difference to our weather. Close quote. It has nothing to do with how close we are to the sun and has everything to do with the tilt of the earth. Here's what that means. Earth's axis is an imaginary pull. It goes right through the center of the earth from the top to the bottom. Earth spins around this imaginary pull, making one complete turn each day. We go from in the sun to away from the sun. That would all be fine and dandy, except for this axis is not straight up and down. Basically, when you look at a picture of the earth, it always looks straight up and down, right? But in all actuality, the earth is tilted as it rotates through our solar system. And that tilt is what determines the season, not the proximity to the sun, but the tilt of the earth. Let me explain. And to do that, I need to introduce two new words to our podcast vocabulary. The words are equinox and solstice. And these events are how the dates of the seasons are determined on our calendars. Equinox and solstice. Remember how I said in an earlier episode that English is a cornucopia of different languages? Yep, equinox is one of those words. The word equinox is derived from two Latin words, equis meaning equal, and nox meaning night. So the word equinox literally means equal night. At the equator, the sun is directly overhead at noon on the equinox. Now here's the deal. Because our world travels cyclically around the sun, there are actually two equinoxes each year, spring and fall equinox, vernal and autumnal. Here's what the US Weather Channel says about that. Quote: There are only two times of the year when the Earth's axis is tilted neither toward nor away from the sun, resulting in a nearly equal amount of daylight and darkness at all latitudes. These events are referred to as equinoxes or equal nights. Close quote. The other side of that coin is what's called a solstice. And the solstice happens in summer and in winter. So equinox, spring, fall, solstice, summer, winter. The summer solstice occurs at the moment the Earth's tilt toward the sun is at a maximum. Therefore, on the day of the summer solstice, this is the longest day of the year. And the winter solstice is then the shortest day of the year for sunlight. So equinox equal night. Equinox happens in the spring and in the fall. Solstice, summer solstice, longest day of the year. Winter solstice, shortest day of the year. So the next question then becomes how do these positions of the tilt of the earth determine the dates of our seasons? Well, the first day of spring just happens to be the vernal equinox or the spring equinox. The vernal equinox is called astronomical spring. Scientifically, that is the first day of spring. This is normally between March 19th to 21st, depending on the year. It's actually very predictable. The first day of summer, called astronomical summer, is determined by the summer solstice. So if you look at a calendar and it says summer solstice, that's also the first day of summer. Now we're talking about the northern hemisphere, so everything above the equator. But what if you live somewhere like Australia that's in the southern hemisphere on the other side of the equator? Well, they're just the opposite. The northern hemisphere has their summer solstice in June, and the summer solstice in the southern hemisphere is in December. A great way to think about this is when you think about Christmas. During Christmas, in Australia, it's actually the middle of their summer. However, in the northern hemisphere, our Christmas, December, is in the middle of winter. That's all due to the Earth's tilt. But it does make one wonder, how long have humans been aware of the tilt of the Earth? How long have we observed things like the equinox and the solstice? Well, the answer is quite a doozy. According to every historical guide I could find, as well as the officials at NASA, humans have known and observed the equinox and solstice cycle as far back as 5,000 years ago. And how do we know that scientists know that ancient peoples knew about the equinox? Well, there's a lot of evidence for it actually. Those ancient peoples left us a lot of evidence about their acknowledgement of the equinox and solstice. We have monuments like Stonehenge in England and Manjara in Malta that date all the way back to the Neolithic era. That's 300 to 4000 BC. And these structures are aligned with the equinox sunrise. We also have ancient monuments like the Great Sphinx of Giza. It's believed to align with the equinox sun and the Mayan pyramid at Chichen Itsa creates a serpent of light on its steps during the equinox. Not a coincidence, it was by design. We also have ancient records. The Persian New Year, called Nauras, has been celebrated on the spring equinox for over 3,000 years. Basically, we have a lot of evidence that these people knew about the equinox and not just knew, they celebrated it. It was a part of their religions, of their cultures, and their lives. So for us modern day folks, the equinox and the solstice is just something that pops up on our Google calendar and says, hey, by the way, it's the first day of spring. But for these ancient peoples, it was a celebration, a rebirth, and a change of the seasons. Unironically, winter solstice has always been important to me. Let me explain why. There was a time in my life when I lived in Eastern Europe. I was coming up on my second winter there, and it was right before Christmas time. It was cold, it was lonely, I was far from home, I was homesick, and I had a roommate, Mackenzie. We're still friends to this day. Shout out Mackenzie! And we were both really struggling. I woke up one morning and I turned to her and I said, It is winter solstice today. This is the darkest it's gonna get. This is the worst it can be. From this day on, at least the sun will be a little bit brighter. And I hope that you guys kind of take that with you too. Remember that no matter what, the days will get longer and the sun will shine bright again. And with that, I'm Mimi Fots, and this has been yet another episode of Hello from the Van