Give or take. 1 pixel size (on the sun from this camera distance) would amount to 1000 miles.
Not taking into account orbital inclination, Magnitude Linear Sight. This comet would be no bigger (averagely) than say 5km across.

That gives you a scale of depth, a Comets tail isn't compacted mass. Its simply vapor being torn away from the nuclei by Solar Heating, like a kettle steaming in effect.