Follow Slashdot stories on Twitter

 


Forgot your password?
Close
typodupeerror
×
Space

The Corkscrew Meteor 43

Posted by michael from the knuckleball dept.
startleman writes "Over on Space.com is an interesting image of a corkscrew meteor. 'On Jan. 1, 1986, [Jimmy Westlake] was photographing [Halley's comet] through his homemade 8-inch reflecting telescope..."About one minute into the exposure, I watched a meteor zip through the field of the telescope." When he developed the roll of slide film, he was astounded that '...Crossing the tail of Halley's comet was a corkscrew meteor trail with no fewer than 25 twists in it.' Westlake's photo was never published until today. He wonders if there are others out there."
This discussion has been archived. No new comments can be posted.

The Corkscrew Meteor More

The Corkscrew Meteor

Comments Filter:

  • Hmm (Score:3, Insightful)

    by PrvtBurrito ( 557287 ) on Friday January 07, 2005 @10:07PM (#11294053)
    Although I have never seen it in a photograph, couldn't this have been caused by visual waves caused by the atmosphere? Anyone who has looked through a telescope in (crappy) skies knows that objects appear to oscillate rapidly. I don't doubt that a meteor could travel in such a way as to pick up on this. The reason the stars don't appear in this way is because they are fixed objects in a time lapse photo and are averages of all the waves. -Sean

    • Re:Hmm (Score:5, Interesting)

      by Theory of Everything ( 696787 ) on Friday January 07, 2005 @10:53PM (#11294296)
      Although I have never seen it in a photograph, couldn't this have been caused by visual waves caused by the atmosphere?

      I believe that you may almost be on to something. IAAA (I Am An Astronomer) and the "visual waves" you speak of are called "seeing"--atmospheric turbulence tends to blur out the images of stars. Though stars are generally sized 1/1000 of an arcsecond (the largest is about 50/1000), the atmosphere blurs on a scale of a few arcseconds. So if the "corkscrew" were caused by seeing, one would expect the stars to be blurred by an amount similar to the amplitude of the "corkscrew", which we do see in the image.

      However, seeing (turbulence) is random. The "corkscrew" is clearly not--it appears sinusoidal. A much more likely explaination is that the telescope mount is vibrating--this would cause sinusoidal smearing of all objects in the field. the meteor, which is moving, becomes a corkscrew; the stationary stars get smeared in the direction of the vibration (as is seen in the picture). The meteor appears about 1 minute into the "2 minute exposure", and has "25 corkscrews", so the vibration is at about a half a hertz. Thus it is likely that his mount wasn't quite sturdy enough for the 'scope, or winds were abnormally high that night. Alternatively, since he apparently accounts for sidereal motion (the telescope has electronic drives to track stars, compensating for the earth's rotation), maybe the drive motors have noise at half a hertz....
      • Looks like a bleedin' contrail to me...
        • It's not a contrail, look how it goes BEHIND the lamppost! Clearly not a contrail. I say insect!

      • Re:Hmm (Score:5, Insightful)

        by Some guy named Chris ( 9720 ) * on Friday January 07, 2005 @11:58PM (#11294638) Journal
        The meteor appears about 1 minute into the exposure, but it doesn't take 1 minute for the meteor to cross the field of exposure, which is what you are implying by your "half a hertz" oscillation theory.

        Now, the motors could have had a 60 hertz "hum" and the meteor was in the frame for just under half a second. That cycle rate is common for AC in North America, and I can belive a meteor streaking across the sky in half a second more than I can believe it streaked across the sky in a whole minute.

        • Yes, indeed (Score:3, Informative)

          by barakn ( 641218 )
          The assumption of a 60 Hz hum and 25 twists implies a total visible travel time of .42 seconds, which seems about right. The fact that the trail isn't more smeared is an indication that the meteor trail is made by a swiftly moving light source that would look like, if we could have taken a very short duration exposure, more like a point source than a bright coma followed by a tail of brightly glowing plasma. The roughly constant production of light along the trajectory and its length suggests that the met

      • Re:Hmm (Score:3, Insightful)

        by Almost-Retired ( 637760 )
        With all due respect to all the theories being tossed otu as 'obvious facts', but which given the time frame cannot be, let me throw out another theory that fits the evidence a lot better than gearing errors in the scope mount or wind induced vibrations, considering that the meteor probably went across the field of view in 3 seconds or less.

        How about if the meteor itself was spinning? Would this not tend to create the effect shown? These things are not always made out of uniform material, and aren't ofte

        • Re:Hmm (Score:3, Interesting)

          by helioquake ( 841463 )
          Gene, your explanation is unlikely.

          The light of a meteor originates from super-heated plasma that forms in front of a meteor, as it drags through air at a high speed. It is not a part of a meteor body itself that is glowing and spinning as it run across the sky.

          Besides, these meteors (that disintegrates) are very small (less than an inch). I doubt that we would see any significant sign of spinning if it is so small (the oscillation amplitude of the contrail can imply the scale size of a meteor, which mus
          • I own a Meade DS-10, and unless the wind was blowing across the open end of the tube and setting up a noise such as you would get by blowing across the top of a gallon jug, I cannot see a vibration of that high a frequency in the mount itself. I don't normally haul mine out when its windy, but I have had the wind come out while I was up on a hilltop (I live in town, and if I really want to see, I take it to the tv transmitter site about 2150 feet high & fairly dark if we kill the yard lights), and don't
            • I doubt that wind is the culprit. Like you say, it'd be relatively low frequency oscillation if true (unless this photo was taken with a cheaper mount...Meade produces a solid mount, btw). Often I saw this type of vibration got picked up by a tripod from the ground vibration (jumping up and down, or a car driving by). Or a simple bump in a telescope produces a high-freq, but slow decaying oscillation, too.
          • The killer evidence, to me, is that the direction of blur shown in the field stars is aligned with the motion of the wobbly contrail of the meteor.

            This is because the earth rotates, and is an effect seen regularly in long-exposure photographs of the stars.
            • This guy is using a guidance system to track siderial motion, pal. From what I recall in Hally's comet, the plate scale used in the image is pretty small and in 2 minutes exposure the trace of stars with the siderial motion is much greater than it appears in the photograph.

      • Re:Hmm (Score:2, Interesting)

        by fenris_23 ( 634852 )
        The stars appear smeared in the direction of oscillations yet not the comet. Should the comet not also be smeared in that direction?

        Also, with no vibrations, should not the stars be smeared in the opposite direction of the Earth's rotation? If so - and if the distance of their smears roughly corresponds to the distance at which they should travel across the sky in two minutes (I am not certain that they would travel that far however) - then the vibration theory could be discounted.

        Also note that the a

      • In this [space.com] image the stars are seen to rotate in the opposite direction, but the comet looks more or less the same. The trajectory of the comet seems to compensate somewhat for the earth's rotation.

        The picture we're discussing was taken in Colorado US, this second one in Chili, which explains the opposite rotation of the stars we observe in the two pictures.
        In this second picture the stars are clearly only smeared in the direction of the earth's rotation, where in the one we discuss here they are more or l

  • Lost a chuck, and is wobbling? (Score:5, Interesting)

    by abulafia ( 7826 ) on Friday January 07, 2005 @10:21PM (#11294121)
    I'd guess a piece of it fell off/vaporized (nonuniform portion, etc.), and it is wobbling around its axis as it spins.

    But what do I know, IANAA(stronomer).

    • The meteor probably passed the field of view in under a second, if not then it was a VERY slow meteor. If it were travelling as fast as a normal meteor, and it was in multiple pieces travelling that fast, the gravity would have to have been extreme to keep the parts from flying apart. We're lucky it just grazed our atmosphere or it could have ended all life on earth with it's impact.

      It is much more likely that there was some vibration in the telescope causing it. If the meteor took about 1/2 second to

  • by the way...Comet Macholz (Score:4, Informative)

    by helioquake ( 841463 ) on Friday January 07, 2005 @10:31PM (#11294185) Journal
    Off topic but...Comet Macholz is found right by Pleiades ("seven" star cluster) tonight. I could manage to spot it with a pair of binocular in Boston. It's fairly fuzzy and faint, though.
  • Assuming it isn't just atmospheric, it looks to me like the meteor is long (like a cylinder) and is rotating at an angle that isn't along one of its axes (which is normal, and causes seasons on earth).
  • It looks like all the backround stars have some motion blur. Perhaps the telescope wasn't all that steady during the exposure.

    • Re:Woobly Telescope (Score:1, Interesting)

      by Anonymous Coward
      That would have to be one motherfucker of a wobble to put that much wibble into a trail that lasts maybe a tenth of a second over a two minute exposure.

    • Re:Woobly Telescope (Score:4, Interesting)

      by node 3 ( 115640 ) on Friday January 07, 2005 @11:33PM (#11294520)
      It looks like all the backround stars have some motion blur.

      You think the stars have motion blur, look at the meteor!

      The motion blur of the stars is due to their movement across the sky during the exposure (like also happened with the meteor).

    • Re:Woobly Telescope (Score:5, Interesting)

      by Stoutlimb ( 143245 ) on Friday January 07, 2005 @11:51PM (#11294598)
      I think you are right. When I looked closer at the stars, they seemed motion blurred, but in an elliptical shape. This would happen if the telescope was vibrating back and forth, in one direction. Perhaps if the telescope was on the back of a pickup truck or something we would see this.

      When you look at the wavy meteorite trail, it's not a perfect sine wave. It looks like it was "waving" on an axis that wasn't perpendicular to the direction of travel. In fact, the apparent direction of the waving seems to line up with the stars motion blur. It seems the axis of vibration is rotated twenty or thirty degrees counterclockwise from the direction of the meteor. Because the stars shape and the wave of the meteor are the same, I'm inclined to agree that this is some kind of vibrational anomoly.

      What do you guys think?
      • Cool as it would have been to have been a regular spinning meteor, I'd say you're right. The star movements seem to confirm it. Of course, we could still be massivly off base. Slashdot isn't always the most accurate, but it usually does a good job as a bunk buster.

      • Re:Woobly Telescope (Score:3, Interesting)

        by khrtt ( 701691 )
        When you look at the wavy meteorite trail, it's not a perfect sine wave.

        Perhaps the meteor has a highly irregular elongated shape, and reflects light unevenly as it rotates, producing the irregular trail.
        • That is true, something strange like that could happen. However, it doesn't explain why the stars are blurred in the same direction as the amplitude of the sinusoidal wave of the meteor. Because of this, I still think vibration of the telescope is the most likely culprit.
    • I don't think so. Long exposures of the night sky produce an interesting effect of star trails. An exposure of only several minutes can produce these trails. They will seem to orbit around the north pole. I've taken pictures like this, but I don't have my scanner so I'll have to google an example. If you use a telephoto lens, the trails will appear longer. If you use a wide angle or even a fish eye, you can see how they all orbit around a central point.

      Star trails are really interesting. Reciprocity
  • Come on, how can there NOT be another one there? We like to think we're the greatest thing to happent o the universe since sliced bread. The first time we notice a natural occurence is the first and only time it exists to the general human populace. Given the number of meteors whizzing about throughout the universe, there's no possible way this could be an isolated phenomenon. Let's spend less time on conjecture and more on "Where's the meteor that will wipe out humanity as we know it?"

  • I've seen these. (Score:5, Interesting)

    by Anonymous Coward on Saturday January 08, 2005 @01:50AM (#11295194)
    I've seen meteors do this, with naked-eye observations during one of the more active fall showers a few years ago. In fact, most of the larger or brighter ones seemed to do it with varying intensity. It's not atmospheric distortion. It's way too periodic.

    I've also seen them with second or third order oscillations, making larger spirals like a big, fast, heavy leaf 'fluttering' to the ground.

    I just assumed that it was the meteor tumbling like it's probably going to - considering it's not probably not an aerodynamically stable shape - and just spewing and sputtering ablating matter as it burned up.

    Why is this a mystery? Anyone that's shot irregular flakes of rocks (or, say, pennies) out of a wrist-rocket or slingshot will see that they behave in much the same way - aerodynamically unstable objects tumbling and spinning from drag as they pass through the atmosphere at high speed.
  • It may be possible that the photographer simply inadvertantly bumped the scope, causing it to wiggle while a meteor or satallite temporarily flew in view. Normally it would blur the stars also, but if the wiggling happened only during a small percentage of the total exposure time, then the stars may be generally uneffected.

  • I have seen one (Score:3, Interesting)

    by Anonymous Coward on Saturday January 08, 2005 @05:23AM (#11295788)
    With the naked eye. I was spending the night at Santa Cruz island, Channel Islands, California. It was in November and we had sailed out there to spend the night. It was very clear that night and dark. No city light (I live in Los Angeles). You could see the Milky Way. Then my friend and I noticed little metior streaks, kinda nice. The I saw this large one, it wasn't the line flash you see all the time. This was slower moving and corkscrew. It traveled across the sky and the trail glowed for a few seconds. I though it was something that happens all the time.
  • As the object passes through the atmosfere, it will probally rotate as many suggests - but that must alså mean that the amount of surface that is exposed in front of the meteor and therefore heated to the point of glowing (or burning) changes over time. I do not believe it's a matter of a "skrew" shape.

    I believe it's more likely that a meteor will be subject to some level of rotation as it travels.

    Another question to all those who have seen this kind of meteor, did the meteor seems to stabilize as it
  • Anyone bothered to try to figure out the absolute amplitude of these oscillations? Even from the picture, I suspect you're talking about an object moving in a sinusoidal path, quite possibly of short wavelength and LARGE amplitude. There's energy and aceleration associated with such behavior.

    Need to know distance to meteor, speed of meteor and some estimate of field of view. Then calculate the width and length of the "wobbles". Some enterprising physics student could then calculate how much accelerati

Slashdot Top Deals

C'est magnifique, mais ce n'est pas l'Informatique. -- Bosquet [on seeing the IBM 4341]

Close