The term "Black Sky" is a metaphor used to describe an event with catastrophic consequences that could affect a large population or cause significant damage. Full definition
The radiant heat lost daily by the earth thru black sky radiation is constant since absolute zero is constant. (judithcurry.com)
By day the view from the peak is of a rich blue black sky. (discovermagazine.com)
The Galaxy A7 measures 156.8 x 77.6 x 7.9 mm, weighs in at a hefty 186 grams, is available in Black Sky, Gold Sand, Blue Mist, and Peach Cloud and costs about $ 530. (androidheadlines.com)