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.