Link to purport by A C Bhaktivedanta Swami Srila Prabhupada

Transcript of Bhakti-Shastri class on this verse by Chaitanya

Bg 8.25

dhūmo rātris tathā kṛṣṇaḥ
ṣaṇ-māsā dakṣiṇāyanam
tatra cāndramasaṁ jyotir
yogī prāpya nivartate

Word for word: 

dhūmaḥ — smoke; rātriḥ — night; tathā — also; kṛṣṇaḥ — the fortnight of the dark moon; ṣaṭ–māsāḥ — the six months; dakṣiṇa–ayanam — when the sun passes on the southern side; tatra — there; cāndramasam — the moon planet; jyotiḥ — the light; yogī — the mystic; prāpya — achieving; nivartate — comes back.

Translation: 

The mystic who passes away from this world during the smoke, the night, the fortnight of the waning moon, or the six months when the sun passes to the south reaches the moon planet but again comes back.

So there is a different path, previous verse talks about devayan Path, yan means path, see we have machines which are made Chandrayan for going on Chandra or Mangalayn for going on Mangal, ISRO is setting up machines like this so the idea is that the devayan is a particular path which ultimately leads to liberation, Pitriyan is another path which leads to heavenly planet but it doesn’t leads to liberation so here it is mentioned dhūmo rātris tathā kṛṣṇaḥ, dhūmo is smoke, rātris is night, kṛṣṇaḥ here it refers to dark fortnight so Krishna Paksha, 

ṣaṇ-māsā dakṣiṇāyanam, so in contrast to Utarayan it is Dakshinayan  

tatra, what happens to such people

cāndramasaṁ jyotir, cāndramasaṁ is the moon planet, 

yogī prāpya nivartate, so what happens to the Yogi is, the person who goes there, that person goes to the moon planet and live on the moon for about 10,000 years (by demigod calculations) and then returns back. yogī prāpya nivartate, if a yogi attempts to leave his body in time which is preferable but if he misses that still he will not get zero results, such yogis also gets result but what is the result the yogi gets elevated to Chandra Loka, that means the yogis goes to havens but after staying in Haven, Havens are not eternal, they are long lasting but not eternal, so Yogis comes back to the earth, and in that way yogī prāpya nivartate, and Krihsna describes in next verse He will contrast the two path in one verse.

End of transcription.