There was a great conflict between gods and demons. The gods lost ground and Rahu threw down the Sun-god. This resulted in chaos in the universe, as there was no division of days and nights. The gods approached the creator, Brahma, who appointed sage Atri to officiate as Sun-god for a week. One of these days of chaos is referred to here as a day without the Sun.
Chaos in Ayodhya 2.114.18
There was a great conflict between gods and demons. The gods lost ground and Rahu threw down the Sun-god. This resulted in chaos in the universe, as there was no division of days and nights. The gods approached the creator, Brahma, who appointed sage Atri to officiate as Sun-god for a week. One of these days of chaos is referred to here as a day without the Sun.