dark nebula

/D AA1 R K N EH0 B Y AH0 L AH0/
noun
  1. 1

    A type of nebula that unlike other types of nebulae does not emit or reflect light and therefore appears as a starless region in the sky.

    โ€œHorsehead Nebula is a typical dark nebula, and is famous for resembling the head of a horse.โ€

Source: https://en.wiktionary.org/wiki/dark%20nebula