Reflection- and Dark Nebulae

Other astronomical objects

Reflection nebulae
Reflection nebulae are interstellar clouds of gas and dust that do not emit light themselves, but merely reflect and scatter the light of neighboring stars.

Properties of reflection nebulae:
  • They consist primarily of fine dust particles (similar to soot or silicate dust).
  • Unlike emission nebulae, they are not hot enough to luminesce on their own.
  • They often appear bluish in telescopes or photographs because the dust particles scatter the short-wave, blue light from stars more than the red light (similar to the blue sky on Earth).
  • Typical surface temperatures are only a few dozen Kelvin above absolute zero – they are therefore very cold.

Well-known examples:

  • M45 – the Pleiades (Seven Sisters): The blue nebulae that envelop the stars are classic reflection nebulae.
  • NGC 1435 (Merope Nebula) in the Pleiades.
  • vdB 141 (Ghost Nebula) in Cepheus.
In summary: Reflection nebulae are cosmic "dust mirrors" that reflect starlight back toward us, making it visible.
Dark Nebulae

Dark nebulae are dense clouds of interstellar matter (gas and dust) that block the light from stars and nebulae behind them.

Properties of dark nebulae:

  • They consist predominantly of cold molecular hydrogen (H₂) and dust particles.
  • Their temperatures are only a few degrees above absolute zero (~10–20 K).
  • They do not emit visible light themselves, but appear as black silhouettes against brighter star fields or emission nebulae.
  • Dark nebulae are often the birthplace of new stars: Within them, gas and dust can collapse due to gravity, forming stars or planetary systems.
Well-known examples:
  • Horsehead Nebula (Barnard 33) in Orion.
  • Barnard's Dark Nebula Catalog lists many smaller dark clouds, e.g., Barnard 68 (a small, round, almost opaque cloud).
In short:
  • Reflection nebulae → scatter light (usually bluish).
  • Emission nebulae → glow themselves (through ionization, usually reddish).
  • Dark nebulae → block light (black silhouettes in the sky).

The Iris Nebula (also known as NGC 7023 and Caldwell 4) is a bright reflection nebula in the constellation Cepheus.
The Angel Nebula NGC 2170 is a colorful nebula complex in the constellation of the Monoceros.
Messier 78 at the top right and NGC 2071 at the bottom left in the constellation Orion are reflection nebulae and can already be observed with smaller telescopes.
Van den Bergh 126 and van den Bergh 134 are 2 blue reflection nebulae in the constellation of Vulpecula, surrounded by numerous dark nebulae, in the arrangement of which the silhouette of Nessie can be seen.
The blue reflection nebula VDB 29 at the top left is in the constellation Taurus. The reflection nebula VDB 31 and the teardrop-shaped dark nebulae Barnard 26, 27 and 28 at the bottom right are already in the constellation Auriga.
A reflection nebula in the constellation Perseus, the Embryo Nebula NGC 1333 is a vast star-forming region of young stars less than a million years old.
The Serpens Molecular Cloud contains the reflection nebula vdB123 and several dark nebulae from the Sharples and Lynds catalog of dark nebulae. The molecular cloud is part of the vast Aquila Rift, a very extensive dark region of the Milky Way.
Large amounts of interstellar matter can be found in the Cepheus/Cassiopeia region. This is also where the little-known dark clouds LDN1235 (top right) and LDN1251 (bottom left) from the Lynds catalog of dark nebulae are located.
Large amounts of interstellar matter can be found in the Cepheus/Cassiopeia region. Here also lies the little-known dark nebula LDN 1251 from the Lynds catalog of dark nebulae.
Lynds Dark Nebula (LDN673) is a molecular cloud complex in the constellation Aquila, in the so-called Aquila Rift
LBN 438 (Lynds‘ Catalogue of Bright Nebulae) im Sternbild Eidechse ist Teil von Lacerta OB1, einer riesigen Sternentstehungsregion. Sie ist etwa 1200 Lichtjahre von der Erde entfernt.
The Ghost Nebula in the center of the image was cataloged as van den Bergh (vdB 141) by Sidney van den Bergh in 1966. The embedded stars illuminate the nebula in a brownish light. The bright Iris Nebula, upper right, is excited to glow by hot star HD200775. Both reflection nebulae are in the constellation Cepheus.
Der Kokon-Nebel IC 5146 rechts oben ist ein Sternentstehungsgebiet mit dem eingebetteten offenen Sternhaufen Collinder 470 im Sternbild Schwan. IC 5146 befindet sich am Ende der länglichen Dunkelwolke Barnard 168 und ist mit dieser zusammen Teil einer ausgedehnten Staubwolke.
In the constellation Pegasus is the barred spiral galaxy NGC 7497 surrounded by the molecular cloud MBM 54.
The dust cloud Sh2-73 illuminated by the light of the Milky Way between the constellations Hercules (top left) and the northern crown (Corona Borealis)
Sh2-73 is a dust cloud in the constellation Hercules illuminated by the light of the Milky Way. Nebulae of this type are also known as galactic cirrus clouds.
Barnard 150 is a dark nebula visible in Cepheus constellation. It is also known as the Seahorse Nebula due to its shape.
Emission NebulaePlanetary Nebulae