Boyd’s Bible Dictionary:

The greater light
(Gen. 1:15-18). Worshipped by idolatrous Hebrews (2 Kings 21:3,5; 23:5); and by other nations (Job 31:26-27; Gen. 41:45); furnishes many metaphors (Psa. 84:11; John 1:9; Rev. 1:16).

Concise Bible Dictionary:

The sun was the greater light given to rule the day. The Israelites particularly observed this by beginning their day-time at sunrise (in distinction from 12 o’clock at night), and closing it at sunset, which necessarily made their days and their hours in summer much longer than in winter (Psa. 19:1-6; Psa. 113:3; Psa. 136:8).
SUN WORSHIP. The Israelites were cautioned against worshipping the sun, nevertheless they fell into that idolatry, and set up high places for the sun in Jerusalem (Deut. 4:19; 2 Kings 23:5,11).
SUN STANDING STILL (Josh. 10:12-27). No legitimate objection can be made to the statement that the sun “stood still;” for though it is now known that it is the earth that moves, yet astronomers still speak of the sun rising and setting, and use the word “solstice,” which signifies “sun standing still.” They would doubtless say the same as Joshua said if they were placed in similar circumstances.
The shadow of the gnomon going back ten degrees on the sun-dial in the days of Hezekiah, 2 Kings 20:10, may, as well as the above, have been produced by the light of the sun passing through a more dense medium; but in whatever way God may have chosen to accomplish these miracles, they are wonderful and divinely-given signs.
SIGNS IN THE SUN. These are probably symbolical of the eclipse and change of those in supreme authority over the earth in the latter days (Luke 21:25; Acts 2:20; Rev. 6:12).