Hey there! Imagine it’s your birthday, and you’re celebrating a whole year of amazing experiences. That’s exactly what happened to me! Over the past year, I’ve done some pretty cool things like getting a PhD, meeting science legends like Bill Nye and Neil deGrasse Tyson, and even having a fun arm-wrestling match with Derek from Veritasium. It’s been a whirlwind of a year, and it got me thinking about how we measure time.
Time is a bit like a river. The past flows away behind us, and the future rushes towards us, while we stand in the present moment. Each moment quickly becomes a memory, and we can’t hold onto them forever. So, we mark our journey with things like seconds, minutes, hours, days, weeks, months, and years.
There are so many ways to think about a year. You could measure it in sunrises, sunsets, or even cups of coffee. I drank about 620 cups of coffee this year! Besides making videos, my body has been busy too, growing hair and nails, and creating new red blood cells.
Did you know that while we’re living our lives, our galaxy is moving closer to the Andromeda galaxy? Our solar system is also traveling around the Milky Way. Even our moon is slowly drifting away from Earth. Here on Earth, we’ve traveled around the sun, and the stars in the sky have shifted their positions.
For most of human history, people have used the seasons to mark a year. The word “year” is related to the Greek word “hora,” which means “season.” The tilt of the Earth gives us these seasons. As Earth spins, it wobbles a bit, like a spinning top. Right now, the north pole points to a star called Polaris, but in the future, we’ll have a new North Star.
If you track the sun’s position in the sky every day, it creates a unique shape called an analemma. This shape includes two solstices and two equinoxes. The time between two equinoxes is called a tropical year, which is what our calendar is based on. But a tropical year doesn’t divide evenly into days, so we use leap years to keep our calendar in sync.
Time is something we all know, but it’s hard to describe. Whether we call it a day, a year, or something else, one thing is certain: it keeps moving forward. Thanks to a concept called entropy, time only goes in one direction. Who knows what the next year will bring? I’m excited to find out!
Thanks for joining me on this journey through time. Stay curious, and take a moment to think about your past year before it drifts away!
Gather items that represent your current year, such as photos, small objects, or notes about your experiences. Seal them in a container and write a letter to your future self. Open it in a year to see how much has changed!
Over the course of a few weeks, observe and record the position of the sun at the same time each day. Plot these positions on a chart to create your own analemma. Discuss how this relates to the concept of a tropical year.
Use a stick and a sunny spot to track the length and direction of shadows throughout the day and across different seasons. Discuss how Earth’s tilt and orbit affect the changing seasons and the length of a year.
Imagine you’re an astronaut traveling through space. Write a journal entry describing your journey as our solar system moves through the Milky Way and towards the Andromeda galaxy. Include facts about our galaxy’s movement.
Think about how you can measure your year in different ways, such as the number of books read, hours spent on hobbies, or cups of coffee consumed. Create a chart or infographic to visualize your personal year in numbers.
Sure! Here’s a sanitized version of the transcript:
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[music] It’s my birthday! [cheering] It’s been a year since we uploaded the very first video to It’s Okay To Be Smart, and a lot has happened in the meantime. I got a PhD, I met Bill Nye, I even met Neil deGrasse Tyson. I uploaded over twenty-two hours of video and made many new YouTube friends in the process. I even had a fun competition with Derek from Veritasium in an arm-wrestling match.
A lot can happen in a year, yet it can seem like no time has passed at all. Time is interesting like that; it’s kind of like a river. The past keeps flowing away behind us, and the future keeps rushing towards us, yet we’re here in the moment we call now. As time flows by, each moment becomes a memory, and we can never quite hold onto them. Instead, we must mark our journey with milestones of our own creation: seconds, minutes, hours, days, weeks, months, and years.
How do you measure a year? In daylights, in sunsets, in midnights, or cups of coffee? I’ve had about 620 cups this year, and since coffee’s a diuretic, that means I’ve produced a lot of waste. I’ve also shed quite a bit of skin and hair, most of which I’ve hopefully replaced.
I’ve created more than just YouTube videos this year too, including growth in my nails and hair, countless red blood cells, and other bodily functions. A year can also be a distance; the light from the very first view of my first video would have traveled an incredible distance by now.
We’ve also come a long way together. Our galaxy is closer to our neighboring galaxy, Andromeda, and our solar system has traveled around the Milky Way. Closer to home, our moon is gradually moving away from Earth, which has spun me around a significant distance from my location in Austin, TX.
Earth itself has traveled around the sun, and during our journey, the position of the stars in the sky changes from night to night. The time it takes for a star or constellation to return to the same point in the sky is about 365 days and a bit more. For most of human history, seasons have been the best way to mark a year. The word “year” actually shares a root with the Greek word “hora,” which means “season.”
The tilt of the Earth gives us those seasons. As Earth spins on its axis, it wobbles a bit like a top. Right now, the north pole points toward Polaris, but in the future, we’ll have to choose a new North Star. The universe doesn’t care what we call winter or summer, and that wobble is out of sync with our orbit around the sun.
If we track the position of the sun in the sky every day, it creates a unique shape called an analemma, with two solstices at the top and bottom, and two equinoxes. The time between two equinoxes is shorter than a sidereal year, and we call that a tropical year, which is what we base our calendar on in the west.
No one was around in the beginning to plan any of this, and even a tropical year doesn’t divide evenly into days, so we have to correct it with a system of leap years.
Time is so familiar, but it’s challenging to describe. Whether we call it a day, a year, or something else, one thing’s for sure: it marches on, and thanks to entropy, in one direction: forward. Who knows what the next year will bring, or even tomorrow? I can’t wait to find out.
Thanks, everybody! Stay curious! Why not take a moment to reflect on the past year before it floats too far away?
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Let me know if you need any further modifications!
Time – A continuous, measurable quantity in which events occur in a sequence from the past through the present to the future. – In physics, time is often considered the fourth dimension, alongside the three spatial dimensions.
Galaxy – A large system of stars, gas, dust, and dark matter bound together by gravity. – The Milky Way is the galaxy that contains our solar system.
Solar – Relating to or determined by the sun. – Solar energy is harnessed from the sun’s rays to generate electricity.
Seasons – Periods of the year characterized by specific weather conditions, temperatures, and lengths of daylight, resulting from the Earth’s tilt and orbit around the sun. – The tilt of the Earth’s axis is responsible for the changing seasons.
Earth – The third planet from the sun in our solar system, home to all known life. – Earth is unique in our solar system for its abundant liquid water and life-supporting atmosphere.
Stars – Massive, luminous spheres of plasma held together by gravity, often forming constellations in the night sky. – Stars are born in nebulae and can live for billions of years before dying in spectacular ways.
Year – The time it takes for a planet, such as Earth, to complete one orbit around the sun. – A year on Earth is approximately 365.25 days long, which is why we have a leap year every four years.
Measure – To ascertain the size, amount, or degree of something using a standard unit or instrument. – Scientists measure the distance between stars in light-years, which is the distance light travels in one year.
Entropy – A measure of the disorder or randomness in a system, often associated with the second law of thermodynamics. – As entropy increases, energy becomes more spread out and less useful for doing work.
Analemma – A diagram showing the position of the sun in the sky at the same time each day over a year, typically forming a figure-eight pattern. – The analemma is used to understand the equation of time and the sun’s apparent motion in the sky.
