Monkey Head Nebula (NGC 2174)
A glowing cloud in Orion lit by HD 42088, a hot star of the young cluster NGC 2175. Its outline is about 40 arcminutes across, larger than the Full Moon.
Nebula in Orion.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 76° above the northern horizon at its highest; from Lethem (3.4° N), to 73° above the northern horizon. It is highest at midnight on the night of 21 Dec, 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 3.7° south-west of Tejat.
- 10x50 binoculars: A faint glow around a few stars, from a dark site.
- A small telescope (80 to 100 mm): A faint glow around a group of stars; a UHC or OIII filter brings out its shape.
- A camera: Spans about 40% of an APS-C frame at 800 mm (field 1.7° × 1.1°); needs a tracking mount. The photo above is a Hubble close-up of a small part of it.
How big, how bright, how far
- Size on the sky: 40′ × 30′, 1.3 Moons across (the Moon is about 31′ wide).
- Distance: 5,800 light-years. The light reaching your eye left it about 5,800 years ago.
- True size: 67 light-years across its catalogued outline; light crosses it in 67 years.
Apparent size from OpenNGC (Mattia Verga), CC-BY-SA-4.0.
What it is made of
- Type
- Emission nebula with a young cluster
- Mass
- About 300 times the Sun's mass, in the stars of its cluster NGC 2175
- Age
- About 6.1 million years (range 3.8 million years to 8.5 million years), the age of NGC 2175
What is in it, not measured:
- Ionised hydrogen: glows red where hot stars light it
- Helium and heavier gases: with traces of oxygen, nitrogen and sulphur
- Dust: in dark lanes
- Young hot stars: that light it
How we know: Distance from Gaia parallaxes of the stars of NGC 2175, the cluster inside it: Hunt & Reffert 2024, A&A 686, A42 (Gaia DR3 cluster catalogue, VizieR J/A+A/686/A42), retrieved 2026-10-21: NGC 2175 1,769 pc; statistical 5,707-5,833 ly (16th-84th percentile); Gaia DR3 parallax zero-point systematics (about 0.02 mas) add about 4%. True size: the apparent size times the distance (apparent size: OpenNGC (Mattia Verga, CC BY-SA 4.0), commit 4e2398a2). Mass: Hunt & Reffert 2024, A&A 686, A42 (Gaia DR3 cluster catalogue, VizieR J/A+A/686/A42), retrieved 2026-10-21, NGC 2175: total 295 ± 14 Suns.
More deep-sky objects: Rosette Nebula (Caldwell 49) · Orion Nebula (M42) · California Nebula (NGC 1499) · Iris Nebula (NGC 7023) · Tarantula Nebula (NGC 2070) · Eta Carinae Nebula (NGC 3372)