Chinese New Year (CNY) falls on 19th February this year. That's an unusually late date; CNY generally falls around the beginning of February.

CNY can also fall on 20th February, though that's only happened once in my lifetime.

a. When will CNY next fall on 20th February?
b. Can CNY ever fall on 21st February? If so, when will that happen next?

Quite brilliant, answer of the year!

To elaborate on the 'close cases' see:

http://www.weather.gov.hk/gts/time/conversion.htm,

'The uncertainty in the calculation of the time of moon phases and solar terms decades ahead may be up to a few minutes. If the time of new moon (first day of the lunar month) or solar term is close to midnight, the dates of the relevant lunar month or solar term in the "Conversion Table" may have a discrepancy of one day. Such situation will occur on the new moons on 28 September 2057, 4 September 2089 and 7 August 2097, the Winter Solstice of 2021, Vernal Equinox of 2051, Spring Commences of 2083 and Vernal Equinox of 2084.'

The New Moon on Feb 20 2148 will occur at 5:33am Beijing Time; on Feb 21 2319 at 1.59pm Beijing Time, so fortunately this complexity does not arise.

Incidentally, because of the difference in time zones, Lunar New Year can occur on different days in, say China and Korea, which also celebrates the same festival. The difference is usually one day, but in 1985, for example, the corresponding Tet Festival in Vietnam occurred a whole month earlier (on 21st January): http://www.informatik.uni-leipzig.de/~duc/amlich/calrules_en.html

Edited on January 16, 2015, 9:36 pm

Posted by broll on 2015-01-16 21:23:45