धूमो रात्रिस्तथा कृष्णः षण्मासा दक्षिणायनम्। तत्र चान्द्रमसं ज्योतिर्योगी प्राप्य निवर्तते
dhūmo rātris tathā kṛiṣhṇaḥ ṣhaṇ-māsā dakṣhiṇāyanam tatra chāndramasaṁ jyotir yogī prāpya nivartate
But if he departs in gloom, at night, during the fortnight of the waning moon and in the six months before the winter solstice, then he reaches only lunar light and he will be reborn.
Translated by Shri Purohit Swami
Attaining the lunar light through smoke, night time, the dark fortnight, and the six months of the southern path of the sun (the southern solstice), the yogi returns.
Translated by Swami Sivananda
Word meanings (from the gita/gita dataset)
dhūmaḥ—smoke; rātriḥ—night; tathā—and; kṛiṣhṇaḥ—the dark fortnight of the moon; ṣhaṭ-māsāḥ—six months; dakṣhiṇa-ayanam—the sun’s southern course; tatra—there; chāndra-masam—lunar; jyotiḥ—light; yogī—a yogi; prāpya—attain; nivartate—comes back;