This is easily one of the best looking games in the jam, your use of shaders is very impressive. I like the gradual color changes approaching different planets.
While its a personal design belief that games need choices to be interesting, not every game needs a set goal to be an enjoyable experience. I do like the vast empty feeling that the long travel time conveys. I would have liked if there was more stuff in the ship to interact with during these long travel times. I got the impression that the astronaut enjoys the beauty of space, but it can be boring to pass the time as well. If the game was going for a more story based approach, showing more of the character's story through his spaceship environment would have a lot more impact. Getting a souvenir from each planet would add that slight bit of meaningful progression this game needs.
Great job on the atmosphere, I hope you work on it some more after the jam period ends.