I was on the top of a ferris wheel taking photos with a DSLR Canon EFS 55-250mm lens with 58mm lens hood of the 2014 Canberra Floriade event and its surrounds. I only discovered unknown object by uploading and enlarging digital photos onto my iMac. At first glance, I assumed it to be a dust particle but realised none of my other images had such marks. Possibly a plane? There is an airport nearby and although I have not checked to see the usual flight patterns at the Canberra Airport, it does seem to be descending or ascending. But the particular shape and size of the object and the distance it seems to be, I wanted to ensure a UFO was not sighted therefore am requesting the assistance of MUFON to possibly verify for me.