HORSEHEAD & FLAME NEBULA

The Horsehead Nebula (Barnard 33 or B33) is a small dark nebula in the constellation Orion. It is one of the most identifiable nebulae in the sky due to the dark molecular cloud shaped like a horse's head. The darkness of the Horsehead is caused primarily by thick dust, although the lower part of the Horsehead's neck casts a shadow to the left. The red glow is from ionized hydrogen gas behind the dark nebula.

IC 434 is a bright emission nebula. The Horsehead Nebula is a dark nebula silhouetted against it.

The Flame Nebula (NGC 2024 or Sh2-277) is an emission nebula near the Horsehead Nebula. The bright star Alnitak, the easternmost star of Orion’s Belt, shines energetic ultraviolet light into the Flame, and this knocks electrons away from the clouds of hydrogen gas that reside there. Much of the glow results when the electrons and ionized hydrogen recombine. Additional dark gas and dust lie in front of the bright part of the nebula, and this is what causes the dark network that appears in the center of the glowing gas.

NGC 2023 is an emission and reflection nebula near the Horsehead Nebula.

IC 431 is a reflection nebula near the Flame Nebula.

IC 432 is a reflection nebula near the Flame Nebula.

IC 435 is a reflection nebula near the Horsehead Nebula.

NGC 1981 is an open cluster in the Orion constellation.

Alnitak is a hot blue supergiant as part of a triple star system in the constellation of Orion that includes Alnilam and Mintaka.

Alnilam is the central star of Orion’s Belt in the equatorial constellation of Orion.