Clusters and nebulas

Nebulous objects in the sky not singular celestial bodies but tightly packed clusters of stars. Parts in the Milky Way that contained no stars, termed 'holes,' which allowed for viewing into starless space beyond.
 William Herschel England 1785 Clusters and nebulas

Nebulous objects in the sky not singular celestial bodies but tightly packed clusters of stars. Parts in the Milky Way that contained no stars, termed 'holes,' which allowed for viewing into starless space beyond.