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-   -   What would cause this???? (https://forums.steves-digicams.com/general-discussion-11/what-would-cause-126820/)

ahill876 Aug 2, 2007 10:25 PM

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Back in May I was trying some long exposures to get star trails. Out of about 4 pictures this was the only one that had these trails that didn't follow the stars, they ran vertical. I thought maybe the tripod slowly drifted down but why is it only certain spots. Then I started thinking maybe it was meteors, but why are they all going in only one direction????
I adjusted the contrast and brightness a bit in this one to bring out the oddball trails a bit more. any thought on what it could be??

ahill876 Aug 2, 2007 10:30 PM

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this was taken the same night, and same exposure length (8min) but no vertical lines. Couldn't see that darn tree branch through the view finder though, lol

John at the Beach Aug 3, 2007 6:57 AM

My guess would be satallites, space junk, or high altitude air planes...If it were a meteor, I think you would see a longer trail...Those things move pretty fast, but it could be slow meteor, if there is such a thing...As far a moving in the same direction, your guess is as good as mine, unless it is air planes...They fly in designated "highways in the sky"...I wouldnt think it was the camera slipping because it would cause all your star trails to look funny....Good shot... :O

Corpsy Aug 3, 2007 12:03 PM

I think they are almost certainly meteors, probably small and at high altitude which is why they didn't move very far and didn't appear that bright. They are all going the same direction because a cluster of meteors traveling many light years through space not all going the same direction aren't going to remain a cluster very long.

I really doubt they'd be any of the things John mentioned. None of those things are likely to appear en masse and all be going the same direction spread out in over a dozen places throughout the sky. Also, planes and satellites are usually rather easy to spot moving through the sky because of how fast they are moving relative to the stars. On an 8 second exposure planes and satellites would appear as long, solid streaks similar in brightness to the stars. These objects left a short trail with increasing brightness, indicating that they were probably falling at a sharp angle.

TCav Aug 3, 2007 4:58 PM

Both shots include Polaris (the North Star) so the star trails all rotate around it. Because the straight trails in the first shot vary in brightness, fromvery faint at the bottom to a bright dot at the top, I think you captured a meteor shower over the north pole. The faint trail at the bottom would have been where the meteor entered the atmosphere, and the bright dot would have been where it finally exploded.

Aircraft and satellites would have continued on their way during the entire exposure, and wouldn't vary in brightness. Aircraft navigation lights would have been consistantly bright, and satellites on polar orbits would have been consistantly illuminated by the Sun until they decended into the Earth's shadow.

Each meteor would have been visible for only a short time, but if you look closely, you'll see that the meteor trails are not exactly parrallel. This indicates that the meteors appeared at various times during your exposure.

Congradulations!

fishycomics Aug 3, 2007 5:40 PM

oh no the clarks belt is falling flash gordon series is coming soon

ahill876 Aug 3, 2007 6:25 PM

thanks guys, it's funny that during 2 seperate 8 min exposures on the same night only one had meteors. I also did a 12 min exposure but didn't turn out well

TCav Aug 3, 2007 9:48 PM

ahill876 wrote:
Quote:

it's funny that during 2 seperate 8 min exposures on the same night only one had meteors.
I find it funnier that, even though you used the same exposure settings and the same focal length, there are more and brighter star trails in the first than in the second. Perhaps whatever set of circumstances allowed more star trails to appear brighter also picked up the meteor trails.

And meteor showers sometimes occur in waves. Maybe the first shot caught a wave, while the second one didn't.

And maybe you got lucky.

ahill876 Aug 3, 2007 10:47 PM

TCav wrote:
Quote:

ahill876 wrote:
Quote:

it's funny that during 2 seperate 8 min exposures on the same night only one had meteors.
I find it funnier that, even though you used the same exposure settings and the same focal length, there are more and brighter star trails in the first than in the second. Perhaps whatever set of circumstances allowed more star trails to appear brighter also picked up the meteor trails.

And meteor showers sometimes occur in waves. Maybe the first shot caught a wave, while the second one didn't.

And maybe you got lucky.
in the first post there I mentioned that I fiddled with contrast and brightness abit in photoshop just to make the star trails easier to see, but the original pretty much looks the same.
I know every year there's supposed to be a big meteor shower in mid August called Perseids, think it falls on Aug 12 this year. Maybe everyone can point their cameras at the skys and see what we can get. Not sure what the results would be like in the city though, the pics I posted were taken in northern ontario where there wasn't a whole lot of light pollution

VTphotog Aug 3, 2007 11:16 PM

There are a number of meteor showers every year which occur at about the same time. I think the Leonid shower occurs in the spring , so this may be what you got a part of. Sorry I don't remember more - it's been a long time since Astronomy.

I'm pretty sure that these are meteors, though. Congratulations on a nice capture.

brian


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