Solar calendar facts for kids

A solar calendar is a special way to keep track of time based on the Earth's journey around the Sun. It helps us know when a year starts and ends, and when seasons change. Most calendars we use today are solar calendars.

What is a Solar Calendar?

A solar calendar measures a year as the time it takes for the Earth to complete one full trip around the Sun. This trip is called a tropical year, and it lasts about 365.2422 days. Because a year isn't exactly 365 days, solar calendars often add an extra day, called a leap day, every four years to keep things accurate.

Why Do We Use Solar Calendars?

Solar calendars are super important for many reasons. They help farmers know when to plant and harvest crops, as seasons are linked to the Earth's position around the Sun. They also help us plan holidays, school years, and many other events that happen at specific times each year. Without them, it would be hard to keep track of time and plan for the future!

How Do Solar Calendars Work?

Solar calendars divide the year into months and days. The number of days in each month can vary, but the total number of days in a year is usually 365. Every four years, an extra day is added to February, making it 29 days long instead of 28. This keeps the calendar aligned with the Earth's actual orbit.

Tropical Solar Calendars

Most solar calendars, like the one you probably use, are tropical solar calendars. They are designed to stay in sync with the seasons. This means that the start of spring, summer, autumn, and winter always fall on roughly the same dates each year. This is very useful for agriculture and daily life.

Sidereal Solar Calendars

A sidereal solar calendar measures the Earth's orbit based on its position relative to distant stars, not the Sun. This type of year is slightly longer than a tropical year. Sidereal calendars are mostly used in astronomy, not for everyday life, because they don't line up with the seasons.

Other Types of Calendars

Not all calendars are solar! There are also other ways to measure time:

• Lunar Calendars: These calendars are based on the phases of the Moon. A month in a lunar calendar is the time it takes for the Moon to go through all its phases, from new moon to new moon. The Islamic calendar is an example of a lunar calendar. Because a lunar year is shorter than a solar year, holidays in lunar calendars move through the seasons.
• Lunisolar Calendars: These calendars try to combine both the Sun and the Moon. They use the Moon's phases for months but add extra months every few years to keep the calendar aligned with the solar year and the seasons. The Jewish calendar and the traditional Chinese calendar are examples of lunisolar calendars.

Famous Solar Calendars

Many different solar calendars have been used throughout history.

• The Julian Calendar: This calendar was introduced by Julius Caesar in ancient Rome. It was a solar calendar with 365 days and a leap day every four years. It was a big improvement for its time, but it was slightly inaccurate over many centuries.
• The Gregorian Calendar: This is the most widely used calendar today. It was introduced by Pope Gregory XIII in 1582 to fix the small errors in the Julian calendar. The Gregorian calendar is very accurate and is used by most countries around the world for civil purposes.

See also

In Spanish: Calendario solar para niños