by Chris Peterson » Mon Aug 27, 2012 2:56 pm
owlice wrote:This image was sent in by APOD viewer Peter Craven, who took it near Flagstaff on Monday, 7/30/12. The item of interest, shown in detail in the top image, was reported to be a fairly large meteor with a visible bow shock; this determination was made by an observatory scientist.
What is this, please?
I can't rule out it being a meteor, but suspect otherwise. To a non-telescopic camera, a meteor presents optically as a point source, and appears to have a finite width because of diffraction. This image doesn't appear bright enough to produce its apparent width. If it is a meteor, the ring around it is definitely not a bow shock, nor related to it in any way. Meteors are hypersonic, moving at least Mach 5, and typically much faster. You can't have a detached ring like that, or any interaction with the atmosphere so lateral and distant from the meteor head.
This is what a meteor bow shock looks like- very close and swept back. In addition, the shock is composed of incandescent gas and ablated material. At the height a meteor is burning (tens of kilometers) the air is extremely thin; you don't have enough material to show any visible structure except where it is hot enough to glow.
I think the most likely explanation is something other than a meteor- an odd contrail, perhaps (with the ring just being a coincidental bit of cloud structure), a nearby insect, or simply lens flare or some other internal reflection in the optics.
[quote="owlice"]This image was sent in by APOD viewer Peter Craven, who took it near Flagstaff on Monday, 7/30/12. The item of interest, shown in detail in the top image, was reported to be a fairly large meteor with a visible bow shock; this determination was made by an observatory scientist.
What is this, please?[/quote]
I can't rule out it being a meteor, but suspect otherwise. To a non-telescopic camera, a meteor presents optically as a point source, and appears to have a finite width because of diffraction. This image doesn't appear bright enough to produce its apparent width. If it is a meteor, the ring around it is definitely not a bow shock, nor related to it in any way. Meteors are hypersonic, moving at least Mach 5, and typically much faster. You can't have a detached ring like that, or any interaction with the atmosphere so lateral and distant from the meteor head.
[float=left][attachment=0]2001121731.jpg[/attachment][/float]This is what a meteor bow shock looks like- very close and swept back. In addition, the shock is composed of incandescent gas and ablated material. At the height a meteor is burning (tens of kilometers) the air is extremely thin; you don't have enough material to show any visible structure except where it is hot enough to glow.
I think the most likely explanation is something other than a meteor- an odd contrail, perhaps (with the ring just being a coincidental bit of cloud structure), a nearby insect, or simply lens flare or some other internal reflection in the optics.