Dark Matter? (3part question)?

Question

Scientist say they have discovered dark matter...
1. What is it (laymens terms please)
2. If it does exist, where is it?
3. What is its make up?

Answer 1

1. Nobody knows.
2. Somewhere in the outer regions of galaxies.
3. Nobody knows.

Answer 2

1. dark matter is 'dark' 'matter'. You can see your table because light reflects off it and enters your eye. But what if light (photons) didn't interact with the object, glass is a good example. The photons would pass right though it (not 100% but close) and you would not be able to see it (Have you ever walked into a glass door because you didn't see it). BUT you can still interact with the glass, by touching (or running into it). Dark matter is matter that we haven't found a way to see it yet. Light doesn't reflect off it for example.

2. Dark matter is found in the halo's of galaxies and galaxy clusters. We don't directly detect it there but we can indirectly detect it based on how the galaxies rotates.

3. There are many theorys. WIMPS: Weakly Interacting Massive Particles (massive in the sense that they have mass, not necessarly as massive as you and me but maybe on the order of elementary particles.) MACHOs: Massive Compact Halo Objects is another. Neutrinos were once a candidate for dark matter but have since been determined not to be massive enough to make up what we observe.

Answer 3

Dark matter is an invention of astronomers to try to explain something that may or may not exist.
They consider galaxies are like satellite systems and dark matter is needed to keep them from flying apart.
If it exists it must be distributed throughout space.
It would have to be mass that neither transmits nor blocks light.

Answer 4

It is the stuff between things in space. Yes Sceintists think there is something there, not just empty space. It's makeup is totally unknown right now. Being totally devoid of light, and seeing as humans need light to see things, we can't see what it is right now.
There are experiments ongoing to try and figure out exactly what darkmatter is, but no conclusions yet.