PURPORT

The prathama-sandhya is the beginning of the age. According to astronomical calculation, the age is divided into twelve parts. The first of these twelve divisions is known as the prathama-sandhya. The prathama-sandhya and sesa-sandhya, the last division of the preceding age, form the junction of the two ages. According to the Surya-siddhanta, the prathama-sandhya of the Kali-yuga lasts 36,000 solar years. Lord Caitanya appeared in the prathama-sandhya after 4,586 solar years of Kali-yuga had passed.