Actually, many careers work like that.
Here's his original site where he used to post his works though it looks like it has not been updated in several years. The documentary is from 2008 and the site was last updated late 2011.
The documentary is less about what he's photographing and more about a view of obsession, in this case it just happens to be a specific subject for photography & videography.
I would've like to have heard a bit more about life before the obsession took over, back to when he was (is?) a lecturer in mathematics at Turku University and had a family. His father being stern was mentioned a few time and was given as the reason why Pekka started his interested in astronomy, that it allowed him to be outside at night after his father's imposed curfew time. I also would have liked to have heard a bit of his life outside of the realm of just the mirages since he also photographs other subjects like time lapse star trails and meteorological conditions (with organizations like NASA using his images).