B33 · Barnard 33
| Chinese name | 马头星云(暗星云 B33) |
|---|---|
| Type | Dark nebula |
| Constellation | Ori |
| RA | 05h41m |
| Dec | −02° |
| Apparent magnitude | — |
| Hemisphere | Both hemispheres |
| Best season | Winter |
| Difficulty | Hard |
| Focal length | 中长焦 800–1200mm |
About
Barnard 33 is the catalog designation for the dark dust that forms the Horsehead Nebula, lying about 1,500 light-years away southeast of Alnitak in Orion. This dense column of cold molecular dust gives off no light of its own; it shows up only as a horse-head silhouette against the bright red hydrogen emission of IC 434 behind it. It belongs to the vast Orion Molecular Cloud Complex, with new stars forming inside while its crest is slowly eroded by ultraviolet radiation from nearby hot stars. It is among the most recognizable dark nebulae in the entire sky, almost always imaged together with that red backdrop. Photographers usually frame it alongside the Flame Nebula (NGC 2024) below, making it one of Orion's most classic yet demanding targets.