Juneau a good aurora question?

[George]

Today's APOD (http://antwrp.gsfc.nasa.gov/apod/ap071119.html) shows a beautiful photo of an aurora taken near Juneau, AL. Near the Sun appears to be a comet, though green. Can such comet-like structures exist due to aurora, or is it not an odd green comet?

[Hornblower]

If that bright spot is the Sun, then the picture must be a composite, and the comet-like object could be almost anything.

[grant hutchison]

I think the bright object must be the moon. Here (http://sacredartichoke.com/coppermine/displayimage.php?album=8&pos=14) are the details of the original photo, showing it to be a 30-second exposure night shot.
The auroras I've seen often have comet-like features in their early stages: separate "stripes" in the auroral "curtain" appear before the whole thing joins up. This object doesn't look like one of them, though.

It looks most like a bit of flare from a scratch or spot of dust to me: but I don't know how likely it is that such a thing would pick up only the green aurora light without scattering any of that brilliant moonlight.

Edit: Oh. Here (http://sacredartichoke.com/coppermine/displayimage.php?album=8&pos=18) is another shot, taken the same night with apparently the same camera, which seems to show a similar bit of "flare" associated with a street light, and the third-quarter moon visible above the light.

Grant Hutchison

[George]

I think the bright object must be the moon. Yes, of course, that makes good sense.


Edit:Oh. Here (http://sacredartichoke.com/coppermine/displayimage.php?album=8&pos=18) is another shot, taken the same night with apparently the same camera, which seems to show a similar bit of "flare" associated with a street light, and the third-quarter moon visible above the light. Nice going, Grant. Several of his images demonstrate the problem. I assume it is some sort of odd lens defect, perhaps in the coatings.

[Jeff Root]

I didn't look at much of that very carefully, but I noticed that the
focal length of the camera/lens was given as 12 mm. My experience
is with film cameras. A 12-mm focal length in a film camera would
imply both a wide-angle lens and a tiny format -- like 16 mm film.
Are CCDs in cameras being made so tiny now that a 12 mm lens can
give a view in the norml range, as opposed to wide angle?

-- Jeff, in Minneapolis

[George]

Are CCDs in cameras being made so tiny now that a 12 mm lens can give a view in the norml range, as opposed to wide angle? As Grant's link to the photography details reveals, his camera is a Canon 20D (http://www.sphoto.com/techinfo/dslrsensors/dslrsensors.htm). This respected camera uses a small sensor: 15 x 22.5 mm. The crop factor is 1.6 so it does have a smaller FOV.

I don't see how this might connect to the image aberation.