Elsewhere, I have referred briefly to a “year of the gods” as equaling 360 “human” years. While at first this seems a rather arbitrary construction of time a shift in perspective eliminates the arbitrariness completely. In fact, more than a shift in perspective, a physical shift is required – to the Polar regions!
Consider the region of the world north of the Arctic circle. That regions is known as the Land of the Midnight Sun since the Sun is visible above the horizon for 24 hours (i.e. the Sun does not set) at least once in a year.
The farther north you go from the Arctic circle, the frequency of this phenomena increases until at the North pole the Sun is visible above the horizon for 24 hours over as much as six months (i.e. six months without the sun setting below the horizon). Hence, at the North pole, six solar months become one long day and another six solar months become one long night. Thus, 12 solar months result in a single nychthemeron (day-night pair) at the North Pole. Call this Polar nychthemeron “Deva Day” and you arrive at the basis for the Hindu definition of long count timeframes.
In fact, there is another little-know definition of Ayana (the movement of the Sun caused by the axial tilt of the Earth) which maps directly to this phenomena. The entire period when the Sun is North the equator (from the Vernal Equinox to the Autumnal Equinox) is called the Devayana and the period when the Sun is South of the Equator (from the Autumnal Equinox to the Vernal Equinox) is called the Pitrayana. In fact, some time in the ancient past the terms Uttarayana and Dakshinayan meant exactly these time periods (just interpret “Uttara Ayana” as “Northern Movement” instead of “Northward Movement” and “Dakshina Ayana” as “Southern Movement” instead of “Southward Movement”). Devayana and Pitrayan put together form a Divya Dhina and 360 Divya Dhina are defined to constitute a Divya Varsha.
The Surya Siddhantha does explicitly state all this by placing Mount Meru at the Northern tip of the Earth’s axis and referring to Mount Meru as the land of the Gods. While the treatment is fanciful its basis is sound reasoning based on the shape of the Earth and the observed movement of the Sun.