The Hole In the Sky: What is it?

[Mikk]

I'm currently rereading "Tales from Watership Down" and was reminded of an aspect of the book that both chilled me and left me with questions. Most of the contents of this book and its prequel, "Watership Down" has some features that seem incomprehensible to rabbits [the white sticks, the sign, the floating wood, the hrududu, the train], but we as humans are able to understand them for what they are.

What I can't seem to figure out is what the hole in the sky actually is. Is it an eclipse? What do you think it is?

[Carressa]

I had always thought of the 'hole in the sky' to be either the moon or the sun. Both form a circle,or hole, so it could be taken that way.