Hi Pete, it appears you've instead captured a jet or something. On January 11th, Comet McNaught was located a mere 8° from the Sun. For visual reference, take a peek at this finder chart dated Jan. 8th. The comet would have appeared much lower on the horizon.
4 Feb 2007 8:44am
@Daniel: Hi Daniel,
A Key West news report got my attention about the comet. Hard to be sure, but it enlarged it looks even less like a plane. Thanks....Pete
Pete, I took your two shots that were right after each other, resized them to match eachother (using the lightpost as reference) and overlayed them. The cloud formations are the same even though you've moved a bit. The overlay clearly shows that in the later picture the contrail is smaller and the jet has moved closer to the horizon.
Photography and astronomy is not guesswork, "hard to be sure" just doesn't cut it. There are certain rules of physics and mathemathics you can apply to check. That failing, resize the pictures to match eachother and then compare, that comet would not move closer to the horizon over the course of you taking a few steps.
It's a nice photo... but it's a jet. Just wanted to clear that up.
You might enjoy this gallery of McNaught imagery (the photos will help provide further visual reference for its position over time as well as illustrate how the dust tail would have appeared, had you captured it). Observers in the Southern Hemisphere were treated to a much better display than we received up North; these images taken by Rob McNaught, the discoverer, are my favorites to date.