Deep-Sky Object
Emission Nebula
A glowing cloud of ionised gas.
Interstellar gas excited by ultraviolet light from hot nearby stars, re-emitting visible light — especially the red H-alpha line of hydrogen.
Overview
Interstellar gas excited by ultraviolet light from hot nearby stars, re-emitting visible light — especially the red H-alpha line of hydrogen.
See also
H I Region
A cloud of neutral hydrogen, glowing at 21 cm.
Cometary Globule
A dark cloud with a glowing tail.
Orion Nebula (M42)
A stellar nursery glowing in Orion's sword.
Dark Nebula
A cold cloud blocking the stars behind it.
H II Region
A nursery of stars wrapped in ionised hydrogen.
Diffuse Nebula
Interstellar cloud of gas and dust visible by emission, reflection, or absorption.