It has been hours though using this telescope, my body is beginning to grow week.
Weak, not week. Also, you switch to the present tense after starting in the past. It's best to stick to one.
I believed I was hallucinating at this point, that strange purple mist from the nebula cloud filled the corners of my observatory.
Feels a bit awkward and rushed. Maybe something like. "It felt like I was hallucinating. The strange purple mist from the nebula cloud seemed to fill the corners of my observatory". Overall you have a lot of sentences like this that feel like they would be better off being broken into two parts.
I dismissed them for now due to their fleeting beauty.
This feels weird. Why is he dismissing them because they're beautiful? It seems like a point that could be elaborated on a bit more.
As I got there though the shelf seemed oddly dusty, but I simply brushed that fact aside as I pulled down what I needed.
Another sentence that could be cut down a lot. "As I got there the shelf seemed oddly dusty, but I ignored that." Also, seems like he's dismissing or ignoring a weird amount of things, to the point that it's standing out in a not good way. At some point it just feels like I'm being bashed over the head with some fact. Some subtlety is good.
As the coffee cooked
You don't really cook coffee. Maybe boiled.
A momentary flash of light like a shooting star would form in the mist as it was at its closest to me.
Some sort of reaction or response to all this would be nice to see. Even if it's just a bit of confusion or worry.
The visible gases were all of a lighter shade and occasionally with density it would become darker.
"With density it would become darker" feels awkward.
So there I sat for another period of time, learning all I could from this distant prophet.
Why is it being described as a prophet? I think a different word would fit better. I get the poetic impulse you're going for but it doesn't quite work here.
I knew the door was only five feet ahead of me when I entered the massed gas cloud. I kept walking though expecting to feel a wall but never found one. After walking thirty to fifty feet forward I began to panic, what fresh hell had I discovered. In my fear I took a step back and tripped. I was hyperventilating now but as I hit the ground I fell just outside of the cloud, I thought I had walked a much farther distance but it seems I never made it farther than a foot into the mist.
A lot of choppy, run on writing. Needs to be smoothed out a lot.
The switch into present tense feels weird. I don't think it works well.
