What is the difference between a lunar year and a solar year?


Ever wondered what the differences between a lunar calendar and a solar calendar are? Or even WHAT lunar and solar mean in regards to the year? No worries, I’m here to explain. Most simply speaking, the lunar and solar calendars are just two different ways to measure a year. In the case of a lunar year, it’s the period of 12 lunar cycles.


A lunar cycle is the time it takes for the moon to go from a new moon, or a really small sliver, to full, and then back to new again, a process that takes 29.53 days. This makes measuring a month incredibly simple. All you have to do is look up into the sky on a clear night to get an idea of where you are in any given month. Calendars that measure years lunarly are either 354 or 355 days long, depending on whether they decide to round things up or down. Many ancient calendars and even some current ones are based on lunar cycles. The ancient Sumerians, Babylonians, Jews, Romans, and Greeks all used lunar calendars, and the present-day Islamic calendar, called the Hijri calendar, is still strictly lunar. 


The solar calendar, on the other hand, is based on the time it takes the earth to make a full orbit around the sun, measuring a year at approximately 365 days. The ancient Egyptian calendar was the first to use a solar year to measure time and when Julius Caesar set about revising the Roman lunar calendar with his own Julian calendar, he based it on their solar one instead. The Gregorian calendar, which is used in most of the western world today, is also a solar calendar, based on the Julian calendar. 


Now the difference between the two calendars is a matter of only 10 or 11 days each year, but that can be huge when it comes to the seasons.


In a lunar calendar, months drift from season to season, which is a big pain when it comes to trying to plan planting and harvesting of crops, and seasonal festivals and celebrations. This means that extra “intercalculary” or leap days, weeks, or even months, have to be added frequently to a lunar calendar to keep it in line with the changing seasons. With a solar calendar, on the other hand, months line up to their respective seasons pretty much flawlessly. 


However, like I said before, watching the moon change shape and size is an easy way to determine where you are in a given month and for that reason, there are some calendars which attempt to make the best of both worlds, using a combination of the solar and lunar cycles with “lunisolar” calendars. 


Examples of lunisolar calendars are the Hebrew, Chinese, Buddhist, Korean, Tibetan, and Hindu calendars. Though they don’t all measure things exactly the same, the general gist of this type of calendar is that the dates on them indicate both the moon phases and the point in the solar year-usually by season or which constellation is near the full moon. Many of these calendars must also add leap days, weeks, or months to keep everything lined up but I suppose that’s a small price to pay for knowing you’re in the middle of the month when the moon is full in the sky.


So, what did we learn today? Mostly, that time is funny and no one has ever really figured out how to measure it perfectly. But also that humans throughout history have been able to come up with truly remarkable ways to make sense of the world around them. Hopefully this video has helped you understand the differences between lunar and solar calendars a bit better and if so, please give it a thumbs up. If you want to learn more about calendars, may I suggest my video answering the question of why the new starts in January? I’m Yvonne Page Illustrates and on this channel I search for answers to life’s most burning questions and then share what I learn with you, so if you’re interested in learning new things along with me, please subscribe to this channel and come back soon to learn more with me again. Bye!

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