Quote:
Originally Posted by strongmanmike
H-alpha is a specific deep red light with a wavelength of 656.28 nm and emitted when a hydrogen electron falls from the third to second lowest energy level. Interstellar dust is mostly carbon, silicon and oxygen and not made of isolated Hydrogen atoms, so does not emit any Ha. Sometimes Hydrogen can be mixed in with dust but it is the Hydrogen that is emitting the light if excited and not the dust, so a Ha image is showing the distribution of the free Hydrogen in the image and not the dust.
We do sometimes hear people describing H-alpha images as showing "lots of dust"... but they don't 
Mike |
Yes thank you....understood Mike