bhacakra-nābhau viṣuvad dvitiyam samasūtragam
ayana dvitayan caiva catasraḥ prathitāstutāḥ
The four all-important points are the two solstices and two equinoxes – for these are the sūtra/thread upon which the core of the ecliptic rests.
tad atareṣu saṅkrānti dvitayam dvitayam punaḥ
Two borders are between each point.
bhānor marakara saṅkrānteḥ ṣaṇmāsā uttarāyaṇam
It takes the Sun six months to reach the northern solstice after entering Capricorn;
karkādestu tathavasyāt ṣaṇmāsā dakṣināyaṇam
and six months to reach the southern solstice after entering Cancer.
meṣādyo dvādaśaite māsāstair eva vatsaraḥ
The twelve divisions beginning from Aries are nothing but the months which constitute a year.
sa eṣa udagayana-dakṣiṇāyana-vaiṣuvata-saṁjñābhir māndya-śaighrya-samānābhir gatibhir
The sun moves between the northern solstice, southern solstice, and equinotical points in a cardinal, fixed, and dual manner.
ārohaṇāvarohaṇa-samāna-sthāneṣu yathā-savanam abhipadyamāno
Its rise towards the northern solstice, its fall towards the southern solstice, and its crossing the middle point can be known by observing time.
makarādiṣu rāśiṣv aho-rātrāṇi dīrgha-hrasva-samānāni vidhatte.
The days and nights grow longer and shorter, revealing which of the signs – Capricorn, etc. – the Sun is in.
yadā meṣa-tulayor vartate tadāho-rātrāṇi samānāni bhavanti
When the Sun is in Aries and Libra, the days and nights are equal.
yadā vṛṣabhādiṣu pañcasu ca rāśiṣu carati
tadāhāny eva vardhante
hrasati ca māsi māsy ekaikā ghaṭikā rātriṣu.
When the Sun is in the five signs starting from Taurus, the days grow longer and nights which grow shorter, month by month
yadā vṛścikādiṣu pañcasu vartate
tadāho-rātrāṇi viparyayāṇi bhavanti.
When the Sun is in the five signs starting from Scorpio, the days and nights change in the opposite way.