KnowraEmission nebulaLinked fromLinked fromThe 15 pages that link to Emission nebula, each with the reason it gives.All 15Broader topic 2Related 1Narrower topic 10Compared with 2NebulaBroader topic: This common nebula type shines after nearby energetic stars ionize its gas.William HugginsBroader topic: Its bright lines showed Huggins that some nebulae were gaseous rather than star clusters.