Nebulae and Star Clusters explained

There are several astronomical catalogues referred to as Nebulae and Star Clusters.

A Nebula is a cloud of dust and gas inside a galaxy. Nebulae become visible if the gas glows, or if the cloud reflects starlight or obscures light from more distant objects.

The catalogues that it may refer to:

• Catalogue des nébuleuses et des amas d'étoiles (Messier "M" catalogue) first published 1771
• Catalogue of Nebulae and Clusters of Stars (William Herschel 'CN'/"H" catalogue) first published 1786
• General Catalogue of Nebulae and Clusters of Stars (John Herschel 'GC'/"h" catalogue) first published 1864
• New General Catalogue of Nebulae and Clusters of Stars (Dreyer "NGC" catalogue) first published 1888
  • Index Catalogue of Nebulae and Clusters of Stars (JLE Dreyer's "IC" catalogue)

See also

• Nebula, a type of celestial body
• Galaxy, a type of celestial body formerly referred to as nebulae
• Star cluster or cluster of stars, a type of celestial body