Matsya Purana — Solar–Lunar Motions
दक्षिणे चक्रवत्सूर्यस् तथा शीघ्रं निवर्तते तस्मात्प्रकृष्टां भूमिं तु कालेनाल्पेन गच्छति //
dakṣiṇe cakravatsūryas tathā śīghraṃ nivartate tasmātprakṛṣṭāṃ bhūmiṃ tu kālenālpena gacchati //
In the southern direction, the Sun turns back swiftly, as though moving in a circle; therefore, in a short span of time it reaches the excellent, favoured region of the earth.
This verse is not describing Pralaya; it belongs to cosmological description, explaining the Sun’s directional movement and how it quickly “turns back” in the southern course.
Indirectly, it supports time-reckoning and auspicious scheduling: understanding the Sun’s course underpins calendrical decisions (seasonal timing, travel, agriculture, and ritual observances) expected of rulers and householders in Purāṇic culture.
The verse does not give direct Vāstu rules, but its emphasis on direction (dakṣiṇa) and solar motion aligns with Vāstu/ritual orientation principles where cardinal directions and solar movement guide layout, entrances, and timing of consecrations.