APOD: A Twisted Meteor Trail Over Tenerife (2010 Jun 02)

[Guest]

I think the twisted path may be due to the drift in the camera mount, inasmuch as the star images are fuzzy and somewhat extended in the direction perpendicular to the meteor path, which could indicate a motion of the camera in that direction.

[Craine]

I made the following photo on April 30th 2010 with a Canon EOS Rebel. f/5.6, 40 second exposure at ISO 400. This was in my own backyard in Austell, Georgia, USA. The zoomed in piece shows the same corkscrew motion.

[maomatt]

As a prior poster stated, the trail looks quite similar to that made by some missile re-entry vehicles.

Assuming that the metor if traveling towards zenith, the path is increasing in amplitude. This can be seen in an object that is spinning at a moderate rate, but has a markedly offset center of gravity. The "wobble" created by the spin in conjunction with aerodynmic forces acting on the meteor causes it to precess around it's mean velocity vector. This creates the sprial path seen in the picture.

Look closely at the far left of the trail and you can see it splitting into several distinct trails. This could be the meteor breaking up in the upper atmosphere to eventually demise as it gets lower.

[BobInDSM]

It looks as if the trail is straight close behind the comet, much like a jet contrail. .then deteriorates or breaks apart, much like the contrail. Maybe?

[lewisharry]

we remember that parts of comets often have areas that glow more than the rest of the comet because the material burns off more quickly...... this metor may have been composed of dissimilar materials with only the most flamible burning off at first. As the object slowly rotated this bright spot would be the only area the camera sees so the entire object seems to the camera to be wobbling...... which it's not.
Lewis in San Diego

[DaveMorton]

I don't think it was 'camera shake'. A deviation on the order of arc-seconds would show up in the stars, especially in the inset.

My first question would be: Which end is the tail? Did it enter the atmosphere and somehow acquire angular momentum, or was it already spinning and somehow lose angular momentum?

Using simple observations of other meteor trails as a guide, it's my experience that the "head" of the trail is the one that has suffered the least dispersion. In this case, the right hand end of the trail, making it more distinct. Therefore, the meteor was headed from left to right. I could be wrong, but I'd doubt it.

[sagian]

I did a quick search for similar photos. Apparently, although uncommon, this isn't a unique phenomenon.

http://www.space.com/imageoftheday/imag ... 50107.html

[sagian]

I don't think it was 'camera shake'. A deviation on the order of arc-seconds would show up in the stars, especially in the inset.

My first question would be: Which end is the tail? Did it enter the atmosphere and somehow acquire angular momentum, or was it already spinning and somehow lose angular momentum?

Using simple observations of other meteor trails as a guide, it's my experience that the "head" of the trail is the one that has suffered the least dispersion. In this case, the right hand end of the trail, making it more distinct. Therefore, the meteor was headed from left to right. I could be wrong, but I'd doubt it.

Thank you, Dave. That makes sense to me, since a decrease in angular momentum could be explained by the loss of mass.

[Clyde Springen]

The irregular object hypothesis seems very reasonable. I also noticed the smoothing out after the initial corkscrew maneuver at the beginning of the visible trail. If the object was in a chaotic orientation (i.e. tumbling) it might have a helical path. A variation on volans95's idea is that if it was irregular in shape, it might orient to the least resistance orientation aerodynamically after a short spin.

See Asteroid 4179 Toutatis which has significant rotation in its non-principle axis. (This asteroid is several kilometers across and so is much much larger that the little rock in this discussion.)
http://echo.jpl.nasa.gov/asteroids/4179 ... tatis.html

CHS.

Notice how the meteor's train wobbles quite signifcantly at the begining but has smoothed out by the end. To me. this would indicate an irregular shaped body that has undergone ablation to become less irregular and therefore more stable. I'm not too sure about an animal or the wind knocking the camera/camera mount because that we be just too coincidental - to have the camera bumped in the same split second it took for the meteor to flash across the sky (although I wouldn't rule it out entirely).

This image has been widely discussed in the meteoritics community. The consensus (unanimous as far as I've seen) is that the camera got jarred by wind or maybe an animal. The same effect has been seen on other images where that happened.

[gstormcrow]

Knuckleball meteor!

While that may have been off-hand by the author, consider: All it would take is this being hurled into space by an unknown method, that either because of shape or excessive rates of lopsided spin could cause a mass to move in a non-typical matter. The measure of arc would depend on our distance (unstated/unknown?) ... so who knows. In a broad sense, it may be indicative of intelligence out there somewhere?????

[mfortsm]

Looks like dampening vibration caused by camera shake. Notice symmetrical blur marks around star images.

Look like this to me. The enlarged stars show the movement as faint distortion above and below the star

[Radartech]

Perhaps the answer lies in the fact that the Earth has a natural frequency of between 6-8 Hz, If the camera mount were to have a frequency of let's say 10 Hz then the camera would semi-resonate peroidically with the Earth and periodically 180 degrees out of phase with it producing the effect seen here. The other streak also appears to have a wiggle to it as well suggesting it's the camera not the object. I counted about 7 oscillations and with a 1 second exposure the math seems to work.

[Bill in Brooklyn]

Since the two meteor images in the same photo have identical paths, I must assume this is a motion artifact of the camera.
I do however believe that some meteors and other objects entering the atmosphere will "wobble", if they are non-symmetrical. Those that remember the Apollo program may recall the capsule was designed off balance, so that by rotating the capsule on re-entry (attitude thrusters) , the ship would be able to change the angle of incidence, and thus change course.

[Beyond]

What "I" find amazing about this is that there is so much speculation (5 pages so far) about such a short white line in the sky that has an irregular end on it.
Its such a short line that either it was like a pebble and burned up in that short a distance, or, it just barely touched the Atmosphere on its way by and you might say waved at us. At any rate even in its short duration it left a lot of speculation in its wake.
I have never seen such a Big response from such a little event. Who would have thought??

[Joe Mansfield]

Note that the "wobble" of the trail starts large then the following waves become smaller until it's a straight line. I say a small gust of wind hit the camera just before the meteor appeared and the vibration was dying down.
IF it was an asymetrical object, given the size of most meteors and the great distance they are from us, would we even see a wobble in the trail?

[Joe Mansfield]

Note that the "wobble" of the trail starts large then the following waves become smaller until it's a straight line. I say a small gust of wind hit the camera just before the meteor appeared and the vibration was dying down.
IF it was an asymetrical object, given the size of most meteors and the great distance they are from us, would we even see a wobble in the trail?

Most meteors are no larger than a pebble. They are also 40-75 miles away when glowing visibly. While falling, the object would have to move in a lateral direction at least 1\4 AND BACK repeatedly for us to see it from the ground.
Due to the speeds at which meteors hit our atmosphere, a move of that magnitude seems improbable if not impossible.

[sagian]

What "I" find amazing about this is that there is so much speculation (5 pages so far) about such a short white line in the sky that has an irregular end on it.
Its such a short line that either it was like a pebble and burned up in that short a distance, or, it just barely touched the Atmosphere on its way by and you might say waved at us. At any rate even in its short duration it left a lot of speculation in its wake.
I have never seen such a Big response from such a little event. Who would have thought??

Or, if the event occurred at the beginning or end of the exposure, only part of it was caught... which is more speculation.

[Guest]

There seems to be another fainter streak to the right of the photo. Is it the same meteor, or is it another streak?

Two "meteor trails," both with the same spiral twist, appear in the photo. ...

It's hard to see because of the dark background of the sky, but this is actually a composite view showing the original photo with the observatory, Milky Way, etc., overlayed in the upper left by an inset showing a close up of the meteor trail. Look closely at the upper left quadrant and you can see the boundaries of the inset.

[jman]

On an SLR the mechanical action of the mirror lifting shakes the camera enough to distort a bright star image. It only takes a second to dissipate.
Note the "butterfly wing" blur of the surrounding stars indicates movement in the same direction as the distorted trail.

[Mark B.]

Oops ... didn't see that five pages of posts had been made. Someone else already made the same comment.

Sorry.
mb

It's hard to see because of the dark background of the sky, but this is actually a composite view showing the original photo with the observatory, Milky Way, etc., overlayed in the upper left by an inset showing a close up of the meteor trail. Look closely at the upper left quadrant and you can see the boundaries of the inset.

[sagian]

links to other 'corkscrew' meteor images

http://www.cloudynights.com/ubbthreads/ ... teor_1.jpg
http://www.space.com/imageoftheday/imag ... 50107.html
http://www.mywhitsunday.net/990918_meteor_corkscrew.jpg

Chinese astronomers also give accounts of corkscrew meteors dating back some 3000 years.

[alwezhpy]

I believe the trail is a result of uneven pressures/effects from rapid deceleration while entering our atmosphere. If the core is not spherical, the core could have been spun during entry. Other thoughts?

[TomNorth]

I'm going to suggest that is is a product of tripod vibration - similar to shake, but faster and of a smaller excursion.

What leads me to this is examination of the picture indicating motion (blur) or unsteadiness of the camera, generally in the Y axis of the frame (more like between 1:00 and 7:00.) This can be seen in the 'soft' image quality of static objects and is reinforced by the shape of the star (or planet) in the center of the image. There is also indication of motion in the X axis of the stars- likely a function of the exposure time.

My experience has been that even a fairly heavy duty tripod can be victim of resonant vibration. This can come from obvious angles - basic flimsiness, being bumped during exposure, shutter function, earthquakes ... but also can be a result of wind producing a resonant/sympathetic oscillation in the frame. Ballpark guess in my mind is that meteor lasted about a quarter second - 250 mS - in the exposure, the latter which was likely several seconds. The short time relative to the overall exposure, and relative brightness of the meteor would 'burn in' its image sharply (and with a wiggle) while softening the surrounding objects.

Taking the quarter second value, I can see possibly 8 - 15 sine cycles in the tail. This would equate to a 32 to 60 cycle/second (Hz) vibration. I've observed this in both metal and wooden surveyor's tripods, the latter example on a bright day with a very brisk breeze, and the effect was also noticeable through the mounted transit. The old early masters -Adams, Weston and the like - would try tying a weight, often a sandbag, to the center post or leg ring of a tripod or mount to dampen this.

[LarryB]

There are several keys in the observation... The general path on average is very straight, so an actually twisted path is very unlikely. The farther back along the trail you look, the wider the "wiggles" appear to be, so they are spreading with time thus indicating that they may be vapor ejecta from the meteorite. Even very small inequalities of shape could stimulate a spin action and a perfectly smooth object with unequal vaporization points would cause spin. The pattern is too regular to indicate upper atmospheric wind shear effects so wind is ruled out.

It is possible that atmospheric friction and heat is stimulating vaporization on the forward portions where it conflicts with atmospheric flow working like a lever to rotate and spin the object. Subsequently changed heating loci would tend to continue the spinning action until the object is completely vaporized.

[jrendtel@aip.de]

Two attributes might provide evidence that something bumped the camera. First, assuming the meteor moved left-to-right, the fluctuations in position are dying down. This might be expected were the camera bumped.

Second, the fluctuations all appear to be about a single line. If a meteor were changing its course, why would it keep coming back to the same average line of flight? Other models would have to explain this in some way, but the "bumped camera" model is a natural.

I notice jrendtel@aip.de has posted above and he is the astrophotographer who took this image (and also the President of the International Meteor Organization to boot!). These questions are directed to him: You said there were no animals nearby. Could you yourself have accidentally bumped the camera? Were there any bats around? Could the camera have "settled" on its stand briefly?

- RJN

If you carefully look at the left end of the trail, it seems that is started before the sinusoidal motion started and the brightness increased. That is what made me so curious. Assumed that the object moved from center to the edge, the shape of the waves agrees with a shake at some instant with an exponential decrease of the amplitude. The cause for a possible bump is not obvious. As already said earlier, if something is possible, it might happen. So what can be excluded: at the observatory location there are no bats, no birds or lizards (too cold) at night; the camera tripod is very low (~20 cm above ground); the one rabbit which might exist nearby would not come so close to me and as the surrounding of the solar telescopes is covered by white quartz sand it would have been clearly visible (it is sitting in the shrubs further away). The exposures of 59 s duration / 1 s break for saving the file are driven by an electronic cable release. If I was near the camera, you would see at least a weak unsharp "shadow" of me. I have such images from the end of the observation when I go to the camera to turn it off. Some argued that a very weak quake might have occurred, too faint to feel it. Well, the Canary Islands are volcanic... You asked for the possibility that the camera have "settled" on its stand briefly - cannot exclude this entirely. The large coma and aberration make it difficult to extract possible short time vibration from the image distortion. To sum up, there is at least a chance that the image shows an unusual trajectory, and if we collect such rare observations it might help to find explanations for them. Juergen Rendtel