Vault is supported as if on an axis. Combining these two statements, we may safely infer that the motion referred to is such a motion of the celestial hemisphere as can be witnessed only by an observer at the North Pole.
Let us now turn to another characterestic of the Polar regions viz a day and a night of six months each and examine references to this characterestic, reference to which is found not only in the Puranas but also in astronomical works. Surya-Siddhanta (XII, 67) says "At Meru, Gods behold the sun after but a single rising during the half of his revolution beginning with Aries." Manu describing the divisions of time says (I, 67) "A year (human) is a day and a night of the gods." In Chapters 163 and 164 of the Vanaparvam (Mahabharat), Arjuna's visit to mount Meru is described in detail and we are therein told "At Meru the sun and the moon go round from left to right every day and so do all the stars " Later on, the writer says "The mountain by its lustre, so overcomes the darkness of night, that the night can hardly be distinguished from the day." A few verses further, and we find, "The day and the night are together equal to a year to the residents of the place." Evidently, the writer had a tolerably correct idea of the meteorological and astronomical characterestics of the North Pole. The lustre of the mountain is the splendour of the Aurora Borealis visible at the North Pole. Passing from the Post Vedic literature to the Vedic we find in the Taittiraya Brahmana (III, 9 22, i) "That which is a year is but a single day of the Gods." It is true that the statement, or anything similar to it is not found in the Samhita portion of the Rigveda.
