---
title: "Emission nebula"
id: "emission-nebula"
project: "Interstellar Travel Safety Procedures Publication2"
url: "https://hedronlabs.clickhelp.co/articles/interstellar-travel-safety-procedures-publication2/emission-nebula"
updated: 2026-10-01T08:39:33Z
---

# Emission nebula

##  Emission nebula
 
An emission nebula is a [nebula](https://en.wikipedia.org/wiki/Nebula) formed of [ionized gases](https://en.wikipedia.org/wiki/Ionized_gas) that emit light of various wavelengths. The most common source of [ionization](https://en.wikipedia.org/wiki/Ionization) is high-energy [ultraviolet](https://en.wikipedia.org/wiki/Ultraviolet) [photons](https://en.wikipedia.org/wiki/Photon) emitted from a nearby hot [star](https://en.wikipedia.org/wiki/Star). Among the several different types of emission nebulae are [H II regions](https://en.wikipedia.org/wiki/H_II_region), in which star formation is taking place and young, massive stars are the source of the ionizing photons; and [planetary nebulae](https://en.wikipedia.org/wiki/Planetary_nebula), in which a dying star has thrown off its outer layers, with the exposed hot core then ionizing them.