I took these photos at Mt Dandenong looking out over the Great Dividing Ranges (Victoria, Australia) on the 10th July 2007 with my Pentax*istDL.
Normally one can hear the sound of aircraft and visually able to see it at least 35k away.
The 1st photo was taken at 3.12 the blob in sky, 2nd was taken at 3.30 object at far right,
3rd photo is of a helicopter for comparison.
Regards
CuteCarol