I am proud to say that I have made explore a few times now, but I always wondered if there is a way to increase your odds of making explore and I think I may have cracked it. If you go through the pages of explore (there is one for each day, working backwards), there is 2 to 3 images that appear everyday without fail (I am yet to find a day with out one of the images, yet). So what are these images? They are a Butterfly, A dragon Fly and a Bird.
So I put the theory forward that if you regularly photograph these subjects, then your odds of making explore are increased.
I am yet to put this theory into test, as these subjects don't really interest me.