The most secure base for translating rongorongo texts is the moon calendar in Mamari. The calendar is divided into 8 periods with unequal number of nights:

1
	Ca6-17	Ca6-18	Ca6-19	Ca6-20	Ca6-21
	Ca6-22	Ca6-23	Ca6-24
2
	Ca6-25	Ca6-26	Ca6-27	Ca6-28	Ca7-1
	Ca7-2	Ca7-3	Ca7-4	Ca7-5	Ca7-6	Ca7-7
3
	Ca7-8	Ca7-9	Ca7-10	Ca7-11	Ca7-12
	Ca7-13	Ca7-14	Ca7-15	Ca7-16
4
	Ca7-17	Ca7-18	Ca7-19	Ca7-20
	Ca7-21	Ca7-22	Ca7-23	Ca7-24
5
	Ca7-25	Ca7-26	Ca7-27	Ca7-28	Ca7-29
	Ca7-30	Ca7-31	Ca8-1	Ca8-2	Ca8-3
6
	Ca8-4	Ca8-5	Ca8-6	Ca8-7
	Ca8-8	Ca8-9	Ca8-10
7
	Ca8-11	Ca8-12	Ca8-13	Ca8-14	Ca8-15
	Ca8-16	Ca8-17	Ca8-18	Ca8-19	Ca8-20	Ca8-21
8
	Ca8-22	Ca8-23	Ca8-24	Ca8-25	Ca8-26
	Ca8-27	Ca8-28	Ca8-29

The glyphs in the 8 periods are arranged in two groups, the first of which is redmarked for easy distinguishing. Each one of the red-marked groups starts with a figure holding a moon crescent.

7 of the red-marked groups end with a glyph including a picture of the sun (hetuu type of glyph) and a fish (ika type of glyph). The fishes have their heads up and tails down during waxing moon and heads down and tails up during waning moon. The fish signifies the moon and the conjunction of sun and moon in these glyphs means that the light of the moon is arriving from the sun.