Iris Nebula (NGC 7023)
A cloud of dust in Cepheus lit blue by HD 200775, a young star inside it. At about 1,160 light-years it is closer than the Orion Nebula.
Nebula in Cepheus.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 29° above the northern horizon at its highest; from Lethem (3.4° N), to 25° above the northern horizon. It is highest at midnight on the night of 4 Aug, in the middle of its season. The page works out tonight's rise, highest point and set for both towns in Guyana time (UTC-4), and where the Moon is.
What you'll see
- Your eyes: Not visible to the eye. It lies 5.8° north of Alderamin.
- 10x50 binoculars: A faint glow around a star, from a dark site.
- A small telescope (80 to 100 mm): A soft glow around its star; filters do not help with reflection nebulae.
- A camera: Tiny on camera: it needs 2,000 mm or more of focal length on a tracking mount.
How big, how bright, how far
- Size on the sky: 10′ × 8′, 32% of the Moon's width (the Moon is about 31′ wide).
- Distance: 1,160 light-years. The light reaching your eye left it about 1,160 years ago, around the year 870.
- True size: 3.4 light-years across its catalogued outline; light crosses it in 3.4 years.
Apparent size from OpenNGC (Mattia Verga), CC-BY-SA-4.0.
What it is made of
- Type
- Reflection nebula
What is in it, not measured:
- Dust: scattering a nearby star's light, which is why it looks blue
- Cold gas: that the dust lives in
- A young star: that lights it
How we know: Distance from the Gaia parallax of HD 200775, the star that lights it: Gaia EDR3 parallax via SIMBAD (basic.plx_value, 2020yCat.1350....0G), distance = 1/parallax, retrieved 2026-10-21 (HD 200775: 2.8175 +/- 0.0374 mas). True size: the apparent size times the distance (apparent size: OpenNGC (Mattia Verga, CC BY-SA 4.0), commit 4e2398a2).
More deep-sky objects: North America Nebula (NGC 7000) · California Nebula (NGC 1499) · Monkey Head Nebula (NGC 2174) · Omega Nebula (M17) · Trifid Nebula (M20) · Lagoon Nebula (M8)