(astronomy) a spiral-shaped nebula / (astronomy, obsolete) a spiral-shaped white nebula; these were generally determined to be spiral galaxies in the 20th century

plural of reflection nebula

plural of reflection nebula

(astronomy) plural of absorption nebula

(astronomy) plural of absorption nebula

(astronomy) A dark nebula; a diffuse mass of interstellar gas and dust that absorbs all incident radiation without reemission.

(astronomy) A nebula composed of ionized gases which produce visible light (as distinct from a reflection nebula, which reflects the light produced by neighboring stars).

plural of white nebula

plural of dark nebula

plural of dark nebula