The answer is: It became black as sackcloth of hair

Rev 6 vs 12

The opening of the sixth seal in the Book of Revelation marks a dramatic moment in the apocalyptic narrative, filled with deep symbolism and vivid imagery. When we hear that the sun became "black as sackcloth of hair," it’s not just a cool piece of symbolism—it represents a major cosmic upheaval. Sackcloth, often worn during mourning, signifies loss and grief. So, the darkening of the sun can be seen as a metaphor for spiritual darkness, chaos, and foreboding.

Now, imagine this tidal wave of imagery echoing Biblical themes. For instance, in Exodus, during the ninth plague, there was total darkness over Egypt for three days. The parallel of sun-darkening events serves to remind readers that such cosmic signs have appeared throughout the Bible, offering insight into God's judgment and deliverance.

Trivia note: In ancient times, different civilizations interpreted solar phenomena as omens of change, often connected back to divine power. Interestingly, this motif still resonates in cultural myths, such as solar eclipses being viewed as a time of crisis.

Furthermore, the mention of stars falling (which follows the darkening of the sun) recalls Matthew 24:29, where Jesus speaks of "the sun being darkened," weaving connections across scripture that shine a light on the prevalent themes of change and reckoning found throughout both the Old and New Testaments. So, the imagery in Revelation 6:12 is choke-full of dramatic meaning, imbuing the readers’ imagination with history, hope, and a dose of intensity.