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Year

physical science Maturity 11-13 Vital Level 3 Next article →

A year is a way to measure a long cycle of time. For us on Earth, it is the time it takes to orbit the Sun. To orbit means to travel in a path around a large object. This trip is what creates our seasons. Because the Earth is tilted, our position changes as we move. This tilt causes changes in weather and daylight hours. It also affects how plants grow and how fertile the soil becomes.

Solar system orrery inner planets
Solar system orrery inner planets

In many places, we see four seasons: spring, summer, autumn, and winter. In tropical areas, people often track wet and dry seasons instead.

Measuring a year can be done in a few different ways. A tropical year is about 365 days, 5 hours, 48 minutes, and 45 seconds. There is also a sidereal year, which is about 20 minutes longer. Scientists also use a Julian year as a precise unit of time. A Julian year is exactly 365.25 days long. This equals exactly 31,557,600 seconds.

Solar system orrery inner planets
Solar system orrery inner planets

Scientists use this specific measurement to calculate big things like the distance of a light-year. Other planets have their own years too. For example, a year on Mars lasts about 1.88 Earth years.

Humans use calendars to keep these cycles organized. The Gregorian calendar is the most widely used system today. It is a smart system that uses leap years to stay accurate. A common year has 365 days, but a leap year has 366 days. This happens because the Earth's trip does not land on a perfect whole number of days. In the Gregorian system, 97 out of every 400 years are leap years. This makes the average year 365.2425 days long.

Solar system orrery inner planets
Solar system orrery inner planets

Another system, the Julian calendar, adds a leap day every fourth year.

We also use different names to number our years. Most people use the Gregorian era, which counts from a 6th century estimate of when Jesus was born. You might see this written as AD or CE. Years before this time are called BC or BCE. There are many other ways to count, like the Hebrew calendar or the Japanese imperial eras.

Solar system orrery inner planets
Solar system orrery inner planets

Even the word "year" has a long history. It comes from very old languages like Proto-Germanic. In some cultures, people even used words for "harvest" to mean a year.

Finally, we use the word "year" for many daily activities. An academic year is the time students spend in school. In the United States, students often have 180 days of teaching. In Nepal, the school year starts on July 15. In India, it usually runs from June 1 to May 31. Businesses also use a "fiscal year" to manage their money. This 12-month period does not always match the calendar year. For example, the United States federal government starts its fiscal year on October 1.

Solar system orrery inner planets
Solar system orrery inner planets
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