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Adrewmc t1_iqtm5ht wrote

Reply to comment by nixiebunny in If objects in space are far away, does light get scattered enough that it would look “low resolution” by the time it reaches us? by hau2mk7pkmxmh3u

While I agree most of the scatting is happening in our atmosphere, and that space is mostly nothing, it’s not completely nothing and when there is something there tends to be a massive amount of something there. There is a lot of dust, and there is a lot of space between us any any of there light source there is out there. And anything that we are interested is where a bunch of stuff is. This is why we want to look at the IR spectrum instead of the UV spectrum because IR light scatters much less in the presence of dust, and the UV spectrum of light can be scattered or blocked a lot easier.

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nixiebunny t1_iqtmx52 wrote

Yes, the interstellar medium (ISM) is rather opaque to visible light, but more transparent to infrared. My day job is in millimeter wave radio astronomy, which studies the makeup and behavior of the ISM.

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Ihavepurpleshoes t1_iqvbtqh wrote

What about dark matter? Can it block light or distort it?

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Skarr87 t1_iqvgy61 wrote

Whatever dark matter is, if it truly exists, appears to not interact with the electromagnetic field at all. This means that to light, dark matter doesn’t exist. So it would cause no change to any light passing through it. Dark matter does interact gravitationally so with enough of it one one place it can change the path of light causing a gravitationally lensing effect.

Fun fact, since it doesn’t interact with the EM field dark matter also can’t clump like normal matter does because you need those charge interactions to dissipate energy to slow down enough to clump. So dark matter just sort of oscillates back and forth through the center of gravity like a pendulum. This is why it always looks the same regardless of galaxy and why it’s always bigger than the galaxy.

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Krail t1_iqu4s8l wrote

If I recall correctly, this is why most of what we've seen beyond our galaxy is to galactic "north" or "south". If we aim our telescopes along the galactic plane, there's a ton of dust in the way (the "milky way" you can see with your eyes when in a dark enough location) that makes it hard to see anything past that.

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