Julian year (calendar)

Okay kiddo, you know how we use the calendar to keep track of the days and months, right? Well, sometimes we need to figure out how many days have gone by since a really long time ago. That's where the Julian year comes in.

A Julian year is a really long time - it's actually exactly 365.25 days long. That means it takes that long for the Earth to go around the sun once. And we use the Julian year as a standard for figuring out how long ago something happened.

So let's say something happened 4,000 Julian years ago. That means it happened 4,000 times 365.25 days ago. We use the Julian year as a way to make sure we're all talking about the same amount of time.

But we have to be careful, because sometimes the Julian year is a little bit off. That's because the Earth doesn't actually take exactly 365.25 days to go around the sun - it's a tiny bit less. That's why we have leap years, where we add an extra day to the calendar to make up for it.

So, to sum it up, the Julian year is a really long time that we use as a standard for measuring how long ago something happened. It's 365.25 days long, but we have to be careful because it's not always exact.