I took some photos on a nice sunny day with my old Pentax K-r. I used fixed aperture mode because I like depth of field in photos. Settings for this particular photo are f/5.6, 1/100s, 55mm and ISO200 according to the exif data.
As you can see in this about 2-3 times zoomed in version of my photo, the yellow surface that is lit up by the sun radiates into the shadowy part behind it.
How is this effect called? How can I prevent it?
First few things I can think of are: haze in the air, not-pefectly-clean (including scratches) or not-perfectly-shaped optics, or light reflections inside the optical path