If a photo like this appeared from the deserts of Arizona, many would say the object appearing to be flying in the background, would be a bird or small plane.
However, this photo is from Mars as claimed by NASA.
This is an actual object in 3 dimensions out there in the background. Look at the shading around its edges. The shading gets lighter at the edges indicating this is a real object out there with sun light reflecting more on its top than on its bottom.
It can’t be a dust particle on camera as object is not spotted in other Mars Curiosity images prior or after above image.
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