|Venus, Mars, & Moon in alignment - photo by Junie Quiroga|
|Relationship between Moon, Earth & Sun|
The main reason we started keeping track of time was so we knew when each season would begin and end and we could plant and harvest our crops accordingly. Now of course it's for planning holidays. As the earth moves around the sun it ends up in precisely the same place each year moving thorough the seasons from spring equinox to summer solstice, fall equinox, winter solstice, and back again to spring. For this reason a solar calendar is much more practical than a lunar one yet the lunar one still exists. Why?
The answer of course is religion. While the solar calendar is a practical one, religious people still use the lunar calendar for their important festivals and have what is called a lunisolar calendar. Jewish and Islamic people have a calendar that is 354 days but Jews have made adjustments that allow certain festivals like Passover, a spring festival, to occur after the spring equinox but the Muslim calendar makes no adjustment for Ramadan which must occur in the 9th lunar month and, as a result, is 11 days earlier every year. For Christians, Easter is determined to be the first Sunday after the full moon on or after March 21st, the spring equinox.
It was Pope Gregory XIII who reformed the calendar in 1582 to make up for the difference in accumulated time between the Egyptian solar calendar which, at 365 1/2 days, was actually 11 minutes and 14 seconds too long, and determined January 1st to be the start of the New Year, Still, it took more than 500 years for the rest of the world to agree to this common calendar. Zoroastrians, and many people in the Balkans, Iran, and Central Asia still celebrate New Year's day on March 21st, the spring equinox, and many East Asian countries of course use the Chinese calendar which is also lunisolar and has been adjusted to allow the New Year to fall on the second new moon after the winter solstice, a date somewhere between January 21 and February 20th.