Matsya Purana — Cosmic Architecture of Sun–Moon and the ‘Houses of the Gods’
चन्द्रतः षोडशो भागो भार्गवस्य विधीयते विष्कम्भान्मण्डलाच्चैव योजनानां तु स स्मृतः //
candrataḥ ṣoḍaśo bhāgo bhārgavasya vidhīyate viṣkambhānmaṇḍalāccaiva yojanānāṃ tu sa smṛtaḥ //
One-sixteenth of the Moon is prescribed as the measure of Bhārgava (Venus); and this is remembered as its extent in yojanas, computed from its diameter and also from the circle of its orbit (maṇḍala).
This verse is not about pralaya; it belongs to a cosmographic/astronomical passage defining planetary dimensions and comparative measures (Venus relative to the Moon).
Indirectly, such measures support calendrical and astrological computations used for ritual timing (muhūrta) and state/household observances, but the verse itself is technical astronomy rather than ethical instruction.
No direct Vāstu rule is stated; the practical ritual link is that graha-measure and orbital calculations underpin traditional pañcāṅga-based scheduling for yajñas, consecrations, and other rites.