Related Clues:

• It's blue and high
• Where birds fly
• Blue thing above us
• It is often blue
• Place for birds
• It's above us
• It's blue and vast
• It's vastly overhead
• Big blue expanse
• Material this person's buried under hideaway
• __ & Telescope Magazine
• Casual material
• Material taken from ground put back
• Material dug from ground put back
• 'Red ___ at night . . .'