Matsya Purana — Dhruva as Cosmic Pivot: Motions of Sun–Moon–Planets
एवं श्रुत्वा कथां दिव्याम् अब्रुवंल्लौमहर्षणिम् सूर्याचन्द्रमसोश् चारं ग्रहाणां चैव सर्वशः //
evaṃ śrutvā kathāṃ divyām abruvaṃllaumaharṣaṇim sūryācandramasoś cāraṃ grahāṇāṃ caiva sarvaśaḥ //
Thus, having heard the divine account, they then spoke to Lomaharṣaṇa, asking in full about the courses (motions) of the Sun and the Moon, and likewise about all the planets in every respect.
This verse does not describe Pralaya directly; it marks a transition into cosmology/astronomy by requesting a comprehensive account of the Sun, Moon, and planetary motions.
Indirectly, it supports dharma-based life by grounding calendars, auspicious timings, and ritual scheduling in graha and luminary movements—topics often used for royal administration and household rites in Purāṇic tradition.
No Vāstu rule is stated here, but the requested graha-cāra knowledge underpins ritual timing (muhūrta) that is traditionally applied to temple consecrations, installations, and other saṃskāras.