There is a leap 5th lunar month (intercalary Month), in the Chinese Lunar Calendar year 2009. The following explanation can help you to know why. There are three basic rules for the Chinese Calendar.
Please read the Essence of the Chinese Calendar for detail about Solar Center Point.
The following is the listing of dates and times about new moon days and the Solar Center points. A lunar month not containing a Center Point is a Leap month.
2009 China Civil Calendar
|Month Name||New Moon Date/Time||Zodiac Date/Time||Note|
|4th Lunar Month||04-25 11:22|
|05-05 16:51||Start of Summer (Snake Month)|
|05-21 05:51||Grain Fills (Gemini) - Center Point|
|5th Lunar Month||05-24 20:11|
|06-05 20:59||Grain in Ear (Horse Month)|
|06-21 13:45||Summer Solstice (Cancer) - Center Point|
|Leap 5th Month||06-23 03:35||No Center point|
|07-07 07:13||Slight Heat (Sheep Month)|
|6th Lunar Month||07-22 10:35|
|07-23 00:36||Great Heat (Leo) - Center Point|
|08-07 17:01||Start of Autumn (Monkey Month)|
|7th Lunar Month||08-20 18:01|
There is no Solar Center Point in the lunar month from 6-23-09 to 7-22-09. Therefore this lunar month is assigned as a leap month. The name of the lunar month repeats the previous month. It called leap 5th lunar month.
The assignment of the Leap Lunar Months is very complicate. For more information about the Chinese Lunar Calendar and Leap Month, please read the Essence of the Chinese Calendar.
All the detail Chinese Lunar Calendar conversion information are available at Chinese Lunar Calendar and High-Precision Astronomical Data CD.