यदा मेषतुलयोर्वर्तते तदाहोरात्राणि समानानि भवन्ति यदा वृषभादिषु
पञ्चसु च राशिषु चरति तदाहान्येव वर्धन्ते ह्रसति च मासि मास्येकैका घटिका
रात्रिषु ॥४॥

yadā meṣa-tulayor vartate tadāho-rātrāṇi samānāni bhavanti yadā vṛṣabhādiṣu pañcasu ca rāśiṣu carati tadāhāny eva vardhante hrasati ca māsi māsy ekaikā ghaṭikā rātriṣu

 yadā - when; meṣa-tulayoḥ - in Meṣa (Aries) and Tulā (Libra); vartate - the sun exists; tadā - at that time; ahaḥ-rātrāṇi - the days and nights; samānāni - equal in duration; bhavanti - are; yadā - when; vṛṣabha-ādiṣu - headed by Vṛṣabha (Taurus) and Mithuna (Gemini); pañcasu - in the five; ca - also; rāśiṣu - signs; carati - moves; tadā - at that time; ahāni - the days; eva - certainly; vardhante - increase; hrasati - is diminished; ca - and; māsi māsi - in every month; eka-ekā - one; ghaṭikā - half hour; rātriṣu - in the nights.


Text

When the sun passes through Meṣa [Aries] and Tulā [Libra], the durations of day and night are equal. When it passes through the five signs headed by Vṛṣabha [Taurus], the duration of the days increases [until Cancer], and then it gradually decreases by half an hour each month, until day and night again become equal [in Libra].

Purport