Why does the Iris Nebula glow blue?
Unlike most nebulae dominated by glowing hydrogen gas, NGC 7023 shines mainly by reflected starlight. Fine interstellar dust scatters the blue light of the hot central star, creating the delicate colors that give the Iris Nebula its name.
But the real hidden treasure of this region lies all around it: vast clouds of dark dust drifting through Cepheus, intertwined with extremely faint integrated flux nebulosity illuminated by the combined glow of the Milky Way itself.
This image was captured using a dual-telescope setup operating in parallel under the dark alpine skies of Foppolo, Italy. Combining two fast f/3 systems allowed the faint surrounding dust to emerge in just 9 hours of total integration time.
Technical details:
Dual 114/456 Newtonians + Starizona Nexus 0.75x reducers (f/3)
Dual ASI2600MC Pro
Optolong L-QEF filter
9 hours total integration (4.5h × 2 systems)