Star Points for February 2011 by Curtis Roelle Year of the Rabbit According to the Chinese lunar calendar, the Chinese New Year (CNY) is celebrated on the first day of the first month and expressed as 1/1. From the perspective of our own solar-based Gregorian calendar, CNY changes dates from year to year — sometimes in January, other times in February. The lunar calendar is very old and rather complicated compared to our the simpler solar calendar. This is year 4709 of the lunar calendar and CNY was on February 3rd. It is said that when Budda departed Earth, he invited all animals to come see him off. Only 12 came and so he rewarded them by naming a year after each. This is the rabbit year. Last year was the tiger and before that the ox. Next year is the dragon. The remaining animals are snake, horse, monkey, rooster, dog, ram, pig, and rat. There is also a cycle of five elements superimposed over the animals. This year's element is metal. Someone born this year is a metal rabbit. Next year is the water dragon. Twelve years from now — the next rabbit year — will be a water rabbit year. The remaining three elements are earth, fire, and wood. The combination of the 12 animals and five elements forms a 60-year cycle. A person who is born this year will celebrate their 60th birthday in the next metal rabbit year. A year in the Gregorian calendar has 365 or 366 days, depending on whether or not it is a leap year. This is because an average or mean solar or "tropical" year is currently 365.2422 days in length. Because calendars don't have fractional days, rules governing leap year deal with the accumulating remainders from each year. The lunar calendar has 12 regular months numbered 1 through 12. Each starts on the day of new moon. Astronomically, the lunar month is based on the moon's 29.5 day "synodic period" — i.e., the time from new moon to new moon. Because lunar calendars also don't have fractional days, lunar months are either 29 or 30 days long. There is one big problem here. Twelve lunar synodic periods is only 354 days — 11 or 12 days shorter than a solar year. The trouble is that if lunar years always had exactly 12 lunar months, CNY would precess from year to year through the earthly seasons. In a few years CNY would pass from winter, to autumn, then summer and spring, before returning to winter once again and repeating the cycle. To peg CNY to a specific season, the lunar calendar must be brought into line with the solar calendar. Naturally, this is done through the use of lunar leap years. In our Gregorian calendar the leap year has one extra day, which always follows February 28. However, in lunar leap years an entire lunar month gets shoved in and, based on complex rules, it can occur almost anywhere in the year. The leap month doesn't even have a unique name. It is the same numbered month as the one prior to where it gets inserted into the year. If leap month is inserted after month 8, then the year has two 8 months, one standard and one "intercalary." In China and other Asian countries, the CNY marks the beginning of the Spring Festival. It lasts two weeks and ends with full moon on the 15th day of the new lunar year. The day of the year's first full moon is called the Lantern Festival. This year the lantern festival and full moon is on February 17. We in the west know the February full moon as the "wolf moon" or "snow moon."