You could sit here for weeks with your one hair brush trying to do that - or you could do it with one stroke with an almighty brush. Paint anything you want on the canvas. Create your own world. You better get your coat out, this is going to be a cold painting.
You can spend all day playing with mountains. You can do anything here - the only pre-requisite is that it makes you happy. I guess that would be considered a UFO. A big cotton ball in the sky.