Okay, first off, I have to make a confession. When I first saw the thumbnail of this painting, I thought "What a beautiful painting! Too bad they couldn't get a better picture". You see, I thought the white object in the left corner ... was glare.
Once I clicked on the image, though, I immediately recognized my mistake. And I'm glad I did. This is a gorgeous painting. I love how the reds, like the sands of a dust storm blowing by, combine with the blues of the sky to create that lovely light pink/lavender color.
This actually reminds me of time lapse videos in which the sky's features (Stars and the like) smear across the sky as the earth rotates. Really beautiful and certainly unique. I'm a person who'd be really picky about what kind of art hung in my home... but this I would hang in less than a heartbeat.
Joint compound spread in concentric circles with a wire wisk or broom, you can buy this as a powder mix or pre made at a hardware store next to the sheetrock. Let it dry out for a long time, maybe over a day. Add a layer of primer over the compound. Spay paint the sky background, for the clouds mix water with acrylic paint and drip it down on the canvas laying flat with a sponge. Change colors as you go so they blend slightly while wet. Do this outside and go nuts. Get messy! Let each layer dry completely before you start the next. Do several layers starting with light colors working your way dark. Touch up with acrylic paint and a brush to highlight tones for shadow and light play. Send me a note if you make something this way I would love to see it :]
Speaking as a teacher with a background in this kind of thing, I think the school would probably prefer you used something you make yourself - though using sources has its place, in a personal essay - and especially for something like an application - it's usually better to show them where you, yourself, are coming from, rather than to borrow someone else's painting for your purposes. Otherwise you might give them the wrong impression.