The Iris Nebula, Widefield. Taken from Bone Cave, TN, 4.1 hrs exposure time.

The Iris Nebula is in the center of the frame. Its blueish tint comes from starlight being reflected off of extremely tiny particles of solid matter, up to 10 or even 100 times smaller than dust particles on Earth. It's 6 light years across, and 1,400 light years away.

The dark nebula surrounding the Iris is made of dust particles coated with frozen carbon monoxide and nitrogen, which mostly block light.

Imaging telescope: TPO Ultrawide 180
Imaging camera: ZWO ASI2600MC Pro
Mount: Sky-Watcher EQ6R-PRO
Guiding telescope: ZWO Mini Guide Scope
Guiding camera: ZWO ASI290MM Mini
Software: ZWO ASIAir Pro, Aries Productions Astro Pixel Precessor, Pleiades Astrophoto PixInisight, Photoshop CC

Calibrated, stacked, light pollution removal in Astro Pixel Processor. Color calibration, stretching, curves, Starnet++, Morphological Transformation in Pixinsight. Levels, noise reduction, sharpening, and selective stretching in Photoshop.