The Rare 13-Day Solar-Lunar Eclipse Sequence
Vyasa notes an astronomical anomaly before the Kurukshetra war: two eclipses occurring within a 13-day fortnight (Trayodashi Paksha) instead of the standard 14–15 day lunar half-cycle, alongside Saturn retrograde near Aldebaran (Rohini).
Modern orbital celestial mechanics models (Planetarium & NASA ephemeris software) confirm that a solar eclipse followed by a lunar eclipse within ~13.7 days is a genuine astronomical event that recurs periodically (verified in ~3067 BCE and ~3139 BCE planetary charts).
चतुर्दशीं पञ्चदशीं भूतपूर्वां च षोडशीम्। इमां तु नाभिजानेऽहम् अमावास्यां त्रयोदशीम्॥ चन्द्रसूर्यावुभौ ग्रस्तावेकमासे त्रयोदशीम्।
caturdaśīṁ pañcadaśīṁ bhūta-pūrvāṁ ca ṣoḍaśīm | imāṁ tu nābhijāne 'ham amāvāsyāṁ trayodaśīm || candra-sūryāv ubhau grastāv eka-māse trayodaśīm ||
“A lunar fortnight has been known to be 14, 15, or 16 days; but this one I know to be 13 days. Both the moon and the sun are eclipsed in the very same month within thirteen days.”