Common year facts for kids

A common year is a year that has 365 days. It's different from a leap year, which has an extra day. In the Gregorian calendar, which most of the world uses, a common year has exactly 52 weeks and one day.

This means something cool: if a common year starts on a Monday, it will also end on a Monday! The next year will then start on a Tuesday. For example, in 2019, both January 1st and December 31st were Tuesdays.

Out of every 400 years in the Gregorian calendar, 303 of them are common years. The rest are leap years, which help keep our calendar in sync with the Earth's orbit around the Sun.

What Makes a Year Common?

A common year simply means it doesn't have the extra day that a leap year does. Our calendar needs to be very precise. The Earth takes about 365.25 days to orbit the Sun. To make up for that extra quarter of a day each year, we add a whole day every four years. This extra day is added to February, making it 29 days long instead of 28.

If a year doesn't get that extra day in February, it's a common year with 365 days.

Months in a Common Year

The number of days in most months stays the same every year. Here's how many days each month has in a common year:

• January has 31 days.
• February has 28 days.
• March has 31 days.
• April has 30 days.
• May has 31 days.
• June has 30 days.
• July has 31 days.
• August has 31 days.
• September has 30 days.
• October has 31 days.
• November has 30 days.
• December has 31 days.

So, in a common year, there are 7 months with 31 days, 4 months with 30 days, and just 1 month (February) with 28 days.

How Calendars Handle Years

Over time, different calendars have been used to keep track of days and years.

The Julian Calendar

The Julian calendar was introduced by Julius Caesar way back in 45 BC. It was a big step forward! In this calendar, every four years, February would have 29 days. This was because people knew a year was a bit longer than 365 days. Adding an extra day every four years helped keep the calendar mostly correct.

The Gregorian Calendar

However, the Julian calendar was just a tiny bit off. It added slightly too many leap years over many centuries. This meant the calendar slowly drifted out of sync with the seasons.

To fix this, Pope Gregory XIII introduced the Gregorian calendar in 1582. This is the calendar we use today. The Gregorian calendar made a small but important change to the leap year rule:

• A year is a leap year if it can be divided by 4 (like 2020).
• BUT, if a year can be divided by 100 (like 1900 or 2100), it's NOT a leap year, unless...
• It can also be divided by 400 (like 2000). If it can be divided by 400, then it IS a leap year!

This clever rule makes the Gregorian calendar much more accurate. For example, 2020 was a leap year, but 2019 and 2021 were common years. The year 1900 was a common year (even though it could be divided by 4), because it could be divided by 100 but not by 400. But the year 2000 was a leap year because it could be divided by 400!

This system helps us keep our calendars accurate for a very long time!