What Are Years?

      A year is the time it takes the Earth to go around the Sun once.

There is one year between each of your birthdays.

Every Christmas is one year apart, too.

      One year is very long, so to make life easier we break each year into 12 months.

The 12 months are:

January, February, March, April, May, June, July, August, September, October, November, December

One year is also about 52 weeks long.

There are 365 days in one year!

Well... except for in leap years.

Leap years have an extra day. They have 366 days!

The extra day on a leap year is on February 29th.

Leap years happen every 4 years.

Leap years are...

years that are divisible by 4. ✅
For example, 2020, 2024, and 2028 are leap years.

not years that can be divided by 100. ❎
For example, 1800 and 1900 are NOT leap years.

But if a year is divisible by 400, then it is a leap year. ✅
For example, 2000 is a leap year.

Why do We Have Leap Years?

It actually takes the Earth about 365.242375 days to rotate around the Sun.

A normal year is only 365 days, so something has to be done to "catch up" the extra 0.242375 days a year.

That's what the extra day in a leap year is for.

So, we know that:

1 year = 12 months = 365 days (or 366 days during leap years)

      A period of 10 years is one decade.

      A period of 100 years (or 10 decades) is one century.

BC and AD

Every year has a number.

The current year is 2022 AD.

The United States was founded in 1776 AD, over 240 years ago!

      AD stands for Anno Domini, a Latin phrase meaning "in the year of the Lord."

1 AD is when a man named Jesus Christ was born, over two thousand years ago!

Enough people agreed to call this year 1, that is stuck.

But what are the years before 1 AD called?

They're called BC!

      BC stands for Before Christ.

The first human cities were founded around 7,500 BC.

So 10,000 BC is 10,000 years before Jesus was born.

Tip: 1 AD follows 1 BC. There is no "year 0". That means 2 AD is 1 year after Jesus was born.

Tip: Even though most of the planet uses BC and AD, most of the planet isn't Christian. Lots of people believe lots of different things, and that's fine. The world is more interesting that way.

Now, complete the practice to help you understand more about years.