The Filter

a trawl through the internet, and the gems i find there


Fun facts about the Iris Nebula:

  • The Iris Nebula, aka NGC 7023, is a reflection nebula in the constellation Cepheus.
  • It’s also known as Caldwell 4. Why? Because it’s a Caldwell object! A what object? The Caldwell Catalogue is an astronomical catalog of 109 star clusters, nebulae, and galaxies for observation by amateur astronomers. It was compiled by Sir Patrick Caldwell-Moore.
  • The Iris Nebula lies about 1,300 light-years away from Earth.
  • The dominant color of the nebula is blue, characteristic of dust grains reflecting starlight. Of course, the iris flower is blue.
  • This cosmic flower spans about six light-years across.
  • It’s often studied for the unusual prevalence of Polycyclic Aromatic Hydrocarbons (PAHs), complex molecules that are also released on Earth during the incomplete combustion of wood fires.

(Sources: 1, 2)