How do dark nebulas and bright nebulas differ on astronomical maps?

On astronomical maps and in direct observation, dark and bright nebulae are distinguished primarily by their appearance and interaction with light.1

• Dark Nebulae: These appear as irregularly shaped black patches against the backdrop of space. They are dense, cold molecular clouds that contain significant amounts of interstellar dust, which effectively absorbs and scatters radiation. Consequently, they are identified on maps by their ability to blot out the light of stars located behind them. Because they are often optically inconspicuous, they are frequently detected through other means, such as carbon monoxide emissions.12

• Bright Nebulae: These appear as faintly luminous, glowing surfaces. They are categorized by their ability to emit their own light or reflect the light of nearby stars. Subclasses include reflection nebulae, which scatter light from nearby stars, and H II regions, which glow due to the ionization of hydrogen by hot stars. Other types, such as planetary nebulae and supernova remnants, are distinguished by their specific shapes and origins related to stellar evolution.134