M78 · Messier 78
| Chinese name | M78 反射星云 |
|---|---|
| Type | Reflection nebula |
| Constellation | Ori |
| RA | 05h47m |
| Dec | +00° |
| Apparent magnitude | 8.3ᵐ |
| Hemisphere | Both hemispheres |
| Best season | Winter |
| Difficulty | Moderate |
| Focal length | 中长焦 800–1200mm |
About
M78 is one of the brightest reflection nebulae in the sky, lying about 1,350 light-years away within the Orion molecular cloud complex northeast of the Orion Nebula. Two hot young B-type stars illuminate the surrounding dust, which scatters their light into a striking cobalt-blue glow. Winding dark dust lanes thread the nebula, which hosts dozens of Herbig-Haro objects—glowing knots where young-star jets slam into surrounding gas, evidence of star birth. Nearby companion nebulae such as NGC 2071 share the region. Images often play its cool blue against broad red H-alpha emission around it, suiting a medium-to-long focal length, making it a photogenic reflection nebula in the Orion field.