Definition
Dark matter is non-luminous matter, that cannot be directly detected by observing any form of electromagnetic radiation (light), but whose existence is suggested because of the effects of its gravity on the rotation rate of galaxies and the presence of clusters of galaxies.
http://www.astronomytoday.com/cosmology/darkmatter.html
A cloud of dark matter would effectively block the transmission of light.
Dark Nebulae
Dark nebulae are clouds of dust which are simply blocking the light from whatever is behind. They are physically very similar to reflection nebulae; they look different only because of the geometry of the light source, the cloud and the Earth. Dark nebulae are also often seen in conjunction with reflection and emission nebulae. A typical diffuse nebula is a few hundred light-years across. (NGC 2264 shown; see also the Horsehead Nebula) [img]ftp://ftp.aao.gov.au/pub/dfm_images/aat013.jpg[/img]
http://astro.nineplanets.org/twn/types.html
What astronomers describe as "dust" could just as easily be explained as a cloud of dark matter, which has formed due to gravitational forces.
Tell me unconvinced, does the term "common sense" mean anything to you? It takes common sense to understand that when Jesus said that faith can move mountains He was not telling His disciples to move mountains. Most of what Jesus taught is found in parables.
Matthew 13:10-15
10 And the disciples came and said to Him, "Why do You speak to them in parables?" 11 And He answered and said to them, "To you it has been granted to know the mysteries of the kingdom of heaven, but to them it has not been granted. 12 "For whoever has, to him shall more be given, and he shall have an abundance; but whoever does not have, even what he has shall be taken away from him. 13 "Therefore I speak to them in parables; because while seeing they do not see, and while hearing they do not hear, nor do they understand. 14 "And in their case the prophecy of Isaiah is being fulfilled, which says,
'You will keep on hearing, but will not understand;
And you will keep on seeing, but will not perceive;
15 For the heart of this people has become dull,
And with their ears they scarcely hear,
And they have closed their eyes
Lest they should see with their eyes,
And hear with their ears,
And understand with their heart and return,
And I should heal them.'
NAS