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Fireball or contrail?
Posted: Mon Jan 10, 2011 1:37 am
by owlice
I do not know the answer to this question. Amanda MacDonald wrote:
- Attached is a photo I took on with my iPhone this December 28th at approx. 4:22pm in the country in Quebec, (Canada). I have several more if you'd like to see them.
I was walking west on the train tracks thinking of my new year resolutions when I saw this light travelling horizontally in the west toward the south like an airplane and then it began to descend diagonally (pictured here) for a long minute until it stopped.
I read that it is called a "fireball," but would love to know more.
Here is the image that came with that email:
[attachment=4]Amanda1.jpg[/attachment][/i]
Looked like a fireball to me! In a subsequent email, she sent additional images, and now... I think this might be a contrail, but I don't know. The additional images:
[attachment=3]Amanda_0613.jpg[/attachment][attachment=2]Amanda_0614.jpg[/attachment][attachment=1]Amanda_0616.jpg[/attachment][/i]
I had to reduce the size of the images to post them, but here's a crop from one of the full-sized images that is not reduced:
[attachment=0]Amanda_0613_crop.jpg[/attachment]
What is this, please? Contrail or fireball? Can anyone tell? TIA!!
Re: Fireball or contrail?
Posted: Mon Jan 10, 2011 2:03 am
by rstevenson
Most of the time a contrail gets longer as the plane progresses across the sky. Since this sequence of shots cover only about a minute, and the full length of the contrail should have lasted that long at least, I am sure it's not a contrail.
Rob
Re: Fireball or contrail?
Posted: Mon Jan 10, 2011 2:30 am
by Chris Peterson
owlice wrote:What is this, please? Contrail or fireball? Can anyone tell? TIA!!
It is a contrail. Ones just like this are frequently reported as fireballs.
Re: Fireball or contrail?
Posted: Mon Jan 10, 2011 4:33 am
by BMAONE23
owlice wrote:I do not know the answer to this question. Amanda MacDonald wrote:
- Attached is a photo I took on with my iPhone this December 28th at approx. 4:22pm in the country in Quebec, (Canada). I have several more if you'd like to see them.
I was walking west on the train tracks thinking of my new year resolutions when I saw this light travelling horizontally in the west toward the south like an airplane and then it began to descend diagonally (pictured here) for a long minute until it stopped.
(snip)
I had to reduce the size of the images to post them, but here's a crop from one of the full-sized images that is not reduced:
![Image](http://asterisk.apod.com/download/file.php?id=1694)
What is this, please? Contrail or fireball? Can anyone tell? TIA!!
Thanks for providing the full size crop. Notice how the trail splits into two separate trails near the end? This is a feature of Contrails. The trails form on either side of the aircraft as the engines are located on the wings. Either 2 or 4 engines will produce this same effect. As the air moves around the fuselage, it creates a slight vortex at the rear of the plane. The Hot Exhaust of the Jet engines creates Condensation trails that, because of the vortex, will be slightly pulled toward each other before separating again once they are out of the influence of the rear vortex.
If this were a fireball meteor, it would likely be faster moving and shorter lived
Re: Fireball or contrail?
Posted: Mon Jan 10, 2011 5:07 am
by owlice
I just looked at the EXIF info on the images; times on the four images are:
16:21:25
16:21:29
16:21:34
16:21:42
Don't know whether that'll help or not. If there is some other bit of info that would be helpful, please let me know; thanks!
Re: Fireball or contrail?
Posted: Mon Jan 10, 2011 5:37 am
by Chris Peterson
owlice wrote:I just looked at the EXIF info on the images; times on the four images are:
16:21:25
16:21:29
16:21:34
16:21:42
Don't know whether that'll help or not. If there is some other bit of info that would be helpful, please let me know; thanks!
The times pretty much prove it's not a meteor (not really necessary, since the visual appearance isn't consistent with a meteor, either).
Re: Fireball or contrail?
Posted: Mon Jan 10, 2011 5:07 pm
by owlice
Chris Peterson wrote:owlice wrote:I just looked at the EXIF info on the images; times on the four images are:
16:21:25
16:21:29
16:21:34
16:21:42
Don't know whether that'll help or not. If there is some other bit of info that would be helpful, please let me know; thanks!
The times pretty much prove it's not a meteor (not really necessary, since the visual appearance isn't consistent with a meteor, either).
Because... a meteor would have moved faster/covered more distance in that time? Would not have lasted for 17+ seconds? Both of these? Neither of these?
Re: Fireball or contrail?
Posted: Mon Jan 10, 2011 6:48 pm
by Chris Peterson
owlice wrote:Because... a meteor would have moved faster/covered more distance in that time? Would not have lasted for 17+ seconds? Both of these? Neither of these?
Overlaying the images suggests that the trail length is about another 5 seconds. So given the minimum meteor velocity of 11 km/s, this sequence of images would represent at least 240 km of meteor trail. In reality, a meteor that slow would be very unlikely; slow meteors tend to be around 20 km/s, which would mean over 450 km of meteor travel.
That kind of distance would require the meteor to be moving nearly parallel to the ground. From the vantage point of the imager, the path would have a significant component directly toward or away from the camera, but there is no change in brightness to suggest this. Each image looks the same. There's really no geometry that works.
Meteors that cover hundreds of kilometers over the ground typically generate thousands of witness reports, but nothing was reported. Such meteors are very uneven in intensity, flaring and fragmenting over their path.
Arguing for a contrail are the general appearance: just after sunset, in the direction of the sunset, a contrail is still in sunlight, and picks up the characteristic sunset orange color (seen in both the contrail and on the horizon). Short contrails (those that evaporate behind the plane) typically flare slightly, and as noted previously, usually show two parallel components.
Re: Fireball or contrail?
Posted: Fri Jan 14, 2011 8:51 pm
by luigi
That's a jet contrail at Sunset, if it was very large and lasted several minutes then it was probably by a big airplane.
You can see many more in this google images search for "contrail at sunset"
http://www.google.com.ar/images?um=1&hl ... =&aql=&oq=
You will see they match your images perfectly.
I also thought it was a meteor when I first saw one
![Very Happy :D](./images/smilies/icon_biggrin.gif)
Re: Fireball or contrail?
Posted: Tue Jan 18, 2011 9:50 pm
by owlice
Thank you! Your answers are much appreciated!