Caldwell 4, also known as the Iris Nebula or NGC 7023, is a reflection nebula in the constellation Cepheus, discovered by William Herschel in 1794. Starlight from a young, hot star embedded within it, SAO 19158, scatters off surrounding dust to produce the nebula's characteristic blue glow, and it lies roughly 1,300 light-years from Earth.
Facts
Classification
Constellation CatalogueNew General Catalogue (NGC) 1 Discovery Year In the Other Atlases
In Constellation
Also in Divinity Atlas: the constellation this subject lies in.
Sources
1. Wikipedia (space and spaceflight articles)
Wikimedia Foundation
2. Wikidata: Caldwell 4
Wikidata Q649379, class allow-list match (w-wdresolver-0926)View the Source Iris Nebula (Wikipedia)
Caldwell 4, Wikipedia - lead section, catalogue classification
The Iris Nebula (also known as NGC 7023 or Caldwell 4) is a bright reflection nebula located about 1,300 light years from Earth in the constellation of Cepheus.
Iris Nebula, Wikipedia - lead section, constellation
The Iris Nebula (also known as NGC 7023 or Caldwell 4) is a bright reflection nebula located about 1,300 light years from Earth in the constellation of Cepheus.
View the SourceCaldwell 4 (Wikipedia)
In Group: Emission, Reflection and Diffuse Nebulae, Lead sentenceQuote, In Group: Emission, Reflection and Diffuse Nebulae, Lead sentence
The Iris Nebula (also known as NGC 7023 or Caldwell 4) is a bright reflection nebula located about 1,300 light years from Earth in the constellation of Cepheus.
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