A dense cloud of interstellar dust and gas that appears as a dark silhouette against the brighter background of stars or glowing nebulae. These regions are often sites of future star formation, as their high density and low temperature provide ideal conditions for gravitational collapse.
From Old English 'deorc' (dark) and Latin 'nebula' (cloud), the term developed in the early 20th century when astronomers realized that dark patches in the Milky Way were not empty regions but dense clouds blocking background starlight. E.E. Barnard cataloged many of these objects in the early 1900s.
Dark nebulae are stellar nurseries in disguise! What looks like empty space is actually where stars are about to be born - these clouds are so dense and cold that they block visible light completely, but infrared telescopes reveal the warm protostars already forming inside.
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