Took this with my Sony in 2008 and I believe I had either a grad blue or grad grey filter on and just shot straight into the sun, those filters were pretty strong tho and I always thought they ruined a lot of photos but sometimes they make good moody shots (I think) .... so I use the photos in colour experiments in PS when I am feeling weird
But you apparently didn't use a filter to make the sun's rays so pretty? I know there is a Cokin filter for that, a filter with a star-shaped cutting in it.
I don't have any Cokin filters, lol I honestly just pointed the camera in the that direction with the grad. filter and that is how it turned out .. well they all did now that I go back and look !!