by Chris Peterson » Mon Jan 10, 2011 6:48 pm
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.
[quote="owlice"]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?[/quote]
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.