Srimad Bhagavatam Canto 05, Chapter 21, Text 15

SB 5.21.15

ratha-nidas tu sat-trimsal-laksa-yojanayatas tat-turiya-bhaga-visalas tavan ravi-ratha-yugo yatra hayas chando-namanah saptaruna-yojita vahanti devam adityam.
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
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 Gayatri and other Vedic meters, are harnessed by Arunadeva to a yoke that is also 900,000 yojanas wide. This chariot continuously carries the sun-god.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
In the Visnu Purana it is stated:
 
gayatri ca brhaty usnig
 jagati tristup eva ca
anustup panktir ity uktas
 chandamsi harayo raveh
 
The seven horses yoked to the sun-god’s chariot are named Gayatri, Brhati, Usnik, Jagati, Tristup, Anustup and Pankti. These names of various Vedic meters designate the seven horses that carry the sun-god’s chariot.
Srimad Bhagavatam Canto 05, Chapter 21, Text 14
Srimad Bhagavatam Canto 05, Chapter 21, Text 16