What is the phase of the moon caused by? What is the cycle of phase change

What is the phase of the moon caused by? What is the cycle of phase change

The main reason for the lunar phase is that the moon itself doesn't shine, and it can only shine by reflecting sunlight
The period of lunar phase change is 29.5 days

Qingming Festival, Dragon Boat Festival, Mid Autumn Festival and Spring Festival are four traditional festivals in China
Tomb Sweeping Day:
customs:
verse:
The Dragon Boat Festival:
customs:
verse:
Mid-Autumn Festival:
customs:
verse:
Spring Festival:
customs:
verse:

Tomb Sweeping Day:
Custom: Tomb Sweeping
Poem: Qingming season rain, pedestrians on the road want to die
The Dragon Boat Festival:
Customs: eating zongzi and rowing Dragon Boat
Verse: the Dragon Boat Festival in the summer, when the Qing day long
Mid-Autumn Festival:
Custom: enjoy the moon and eat moon cakes
Poem: I hope people long, thousands of miles together Chan Juan
Spring Festival:
Customs: setting off firecrackers, wearing new clothes and visiting relatives
Poem: the sound of firecrackers in a year, the spring breeze send warm into Tu su

Mid Autumn Festival, new year's Eve, Spring Festival, Double Ninth Festival, Dragon Boat Festival "these traditional festivals are arranged in chronological order. What should be the last one?

In the case of the lunar calendar, it's new year's Eve and December 30 of the lunar calendar