A dark nebula absorbs visible radiation, making it appear dark and blocking the light emitted from behind it. Dark nebulae are composed mostly of cold, dense gas and dust. They are often found in regions where stars are being formed, and they play a crucial role in the process of star formation. The dense material in dark nebulae blocks and obscures the light emitted from stars or other bright objects in the background, making them appear as dark patches against the bright background.
