Matsya Purana — Solar–Lunar Motions
उदग्याने तथा सूर्यः सर्पते मन्दविक्रमः तस्माद्दीर्घेण कालेन भूमिं सो ऽल्पां प्रसर्पति //
udagyāne tathā sūryaḥ sarpate mandavikramaḥ tasmāddīrgheṇa kālena bhūmiṃ so 'lpāṃ prasarpati //
Likewise, when it is in its northward course (udagāyana), the Sun moves with gentle pace; therefore, over a long span of time, it advances only a small distance across the ground.
This verse is not about Pralaya; it is a Vastuvidya-style observation on the Sun’s northward course and its perceived slow progression, useful for time-and-direction based planning.
It supports practical governance and household planning: understanding seasonal solar movement helps in laying out settlements, scheduling works, and aligning buildings for light, heat, and auspicious timing.
It highlights Uttarayana as a factor in orientation and time-measurement (shadow/sun-path awareness), informing Vastu decisions such as axis alignment, courtyard exposure, and seasonally appropriate ritual or construction timing.