ArtCentrics

Nebula

A nebula is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust. Generally nebula are classified as either Emission or Reflection nebula.

Emission Nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star.

Reflection Nebula are clouds of interstellar dust which might reflect the light of a nearby star or stars. The energy from the nearby stars is insufficient to ionize the gas of the nebula to create an emission nebula, but is enough to give sufficient scattering to make the dust visible.

The distinction between these two types of nebula is important since the light resulting from each type is quite different, and this dictates the best to take a photograph of each.