Srimad Bhagavatam Canto 05, Chapter 22, Text 06

SB 5.22.6

atha ca yavatardhena nabho-vithyam pracarati tam kalam ayanam acaksate.
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Thus the time the sun takes to rotate through half of outer space is called an ayana, or its period of movement [in the north or in the south].
Srimad Bhagavatam Canto 05, Chapter 22, Text 05
Srimad Bhagavatam Canto 05, Chapter 22, Text 07