Srimad-Bhagavatam: Canto 5 - Chapter 1 - Verse 15

Sanskrit:

रथनीडस्तु षट्‌त्रिंशल्लक्षयोजनायतस्तत्तुरीयभागविशालस्तावान् रविरथयुगो यत्र हयाश्छन्दोनामान: सप्तारुणयोजिता वहन्ति देवमादित्यम् ॥ १५ ॥

ITRANS:

ratha-nīḍas tu ṣaṭ-triṁśal-lakṣa-yojanāyatas tat-turīya-bhāga-viśālas tāvān ravi-ratha-yugo yatra hayāś chando-nāmānaḥ saptāruṇa-yojitā vahanti devam ādityam.

Translation:

My dear King, the carriage of the sun-god’s chariot is estimated to be 3,600,000 yojanas [28,800,000 miles] long and one-fourth as wide [900,000 yojanas, or 7,200,000 miles]. The chariot’s horses, which are named after Gāyatrī and other Vedic meters, are harnessed by Aruṇadeva to a yoke that is also 900,000 yojanas wide. This chariot continuously carries the sun-god.

Purport:

In the Viṣṇu Purāṇa it is stated: 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.