Leap years
An extra day every four years.
Extra hours
The Earth takes 365 days plus nearly a quarter of a day to go round the Sun.
What happens to the extra quarter days?
What this lesson covers
The idea
Earth's extra quarter day per revolution adds up to about a day in four years, so a leap day is added every four years; in the Gregorian calendar any year divisible by four gets a 29-day February.
Extra hours
The Earth takes 365 days plus nearly a quarter of a day to go round the Sun.
What happens to the extra quarter days?
- They add up to about one day every four years
- They disappear
- They add up to a month every year
Check some years
Look at 2024 and 2026.
A leap day
Every year the Earth takes nearly an extra quarter of a day. These extra hours add up to about one day in four years. So one extra day is added every four years, called a leap year. In the Gregorian calendar, a year divisible by four gets a 29-day February.
4 × ¼ day ≈ 1 day, so a leap day is added every four years. In the Gregorian calendar a year divisible by four has 29 days in February.
Notes
A leap year (divisible by 4) has 29 days in February.
Check yourself
The extra quarter days add up to about one day in …
In the Gregorian calendar, which of these years is a leap year?
How many days does February have in a leap year?
Answer: 29 days
February has 29 days in a leap year.
A leap day keeps the calendar well synchronised with the …
- one year. One year gives only a quarter of a day.
- four years — correct. Yes!
- ten years. They add up to a day in four years.
- 2025. 2025 is not divisible by 4.
- 2026. 2026 is not divisible by 4.
- 2024 — correct. Yes!
- seasons — correct. Yes!
- Moon. A solar calendar matches the seasons.
- tides. A solar calendar matches the seasons.