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Śrīmad-Bhāgavatam
[Canto 5, Ch. 21]
PURPORT
In the  Viṣṇu Purāṇa  it is stated:
gāyatrī ca bṛhaty uṣṇig jagatī triṣṭup eva ca anuṣṭup paṅktir ity uktāś chandāṁsi harayo raveḥ
The seven horses yoked to the sun-god's chariot are named Gāyatrī, Bṛhati, Uṣṇik, Jagatī, Triṣṭup, Anuṣṭup and Paṅkti. These names of various Vedic meters designate the seven horses that carry the sun-god's chariot.
TEXT 16
पुरस्तात्सवितुररुणः पश्चाच्च नियुक्तः सौत्ये कर्मणि किलास्ते ॥१६॥
purastāt savitur aruṇaḥ paścāc ca niyuktaḥ sautye karmaṇi kilāste.
purastāt—in front; savituḥ—of the sun-god; aruṇaḥ—the demigod named Aruṇa; paścāt—looking backward; ca—and; niyuktaḥ—engaged; sautye—of a charioteer; karmaṇi—in the work; kila—certainly; āste—remains.
TRANSLATION
Although Aruṇadeva sits in front of the sun-god and is engaged in driving the chariot and controlling the horses, he looks backward toward the sun-god.
PURPORT
In the  Vāyu Purāṇa  the position of the horses is described:
saptāśva-rūpa-cchandāṁsī vahante vāmato ravim cakra-pakṣa-nibaddhāni cakre vākṣaḥ samāhitaḥ