It's a cute little game! The scaling of difficulty was coming at a good pace for me until stage 6. I gave it ~5 tries.
I expect the controls will cause most players to make the mistake when stopping on the underside of the planet, they'll forget that the left/right is flipped. Having the planet rotating underneath the UFO instead could resolve that, but might make for a different game. The spotting would also sometimes be forgiving or insta-kill and so I was unclear exactly how to maneuver around that mechanic.
The face on the UFO is also a nice cute touch. It looks so smug after a successful scoop :-)
Nice work for 48 hours!