Year facts for kids

A year is the time it takes for the Earth to travel all the way around the sun once. This journey takes about 365 days. Sometimes, we have a special year called a leap year, which has an extra day, making it 366 days long.

Even though our calendars usually show 365 days, the Earth's trip around the sun actually takes a tiny bit longer: about 365 and a quarter days. That's why we add an extra day every four years to keep our calendars in sync with the Earth's orbit.

Most calendars, like the Gregorian calendar we use, start the year on January 1st and end it on December 31st. However, some other types of years, like a fiscal year (for businesses) or a school year, can begin and end on different dates.

Different Ways to Measure a Year

People measure years in different ways, depending on what they need it for.

• A solar year is based on the seasons. The Gregorian calendar follows the solar year. It's about 365 days long. More precisely, a tropical year (another name for a solar year) is the time it takes for the sun to return to the same point in the cycle of seasons, like from one spring equinox to the next.
• A lunar year is based on the moon's cycles. It usually has 12 lunar months. Each lunar month is about 29 days, 12 hours, and 44 minutes long, making a lunar year about 354 days in total.
• A sidereal year measures the time it takes for the Earth to complete one orbit around the sun, when measured against a distant star. It's the time between when a chosen fixed star appears highest in the night sky.
• An anomalistic year is the time between when the Earth is closest to the sun (a point called perihelion). The distance between the Earth and the sun changes slightly throughout the year.
• An eclipse year is the time it takes for the sun to return to a specific point in the sky where eclipses can happen. This is when the sun, Earth, and moon can line up.

Solar and lunar years are often used for daily life and in different calendars. The other ways of measuring a year are mostly used by astronomers, who study space and planets.

Counting Years: No Year Zero

In our common system of counting years, like the Anno Domini (AD) or Common Era (CE) system, there was no "year zero." The years go directly from 1 BC (or BCE) to 1 AD (or CE). This means that the first year was year 1. However, some astronomers use "year 0" for the year 1 BC (or BCE) to make their calculations easier, especially when figuring out leap years that happened a very long time ago.

Measuring Millions of Years

When scientists talk about very long periods of time, especially in fields like geology (the study of Earth's rocks and history), paleontology (the study of fossils), and astronomy, they often use the term Ma. This stands for megaannum, which means one million years.

On this wiki, we often prefer to use the simpler term "mya" which means "million years ago." It's easier for everyone to understand!

See also

In Spanish: Año para niños