You decide
On a closer viewing: Ah, or maybe we're just talking about the streaks that don't line up with the stars.
Vulcan Administrator
You decide
On a closer viewing: Ah, or maybe we're just talking about the streaks that don't line up with the stars.
Everything I need to know I learned through Googling.
Established Member
That looks like one hell of a meteor shower if it is one. I have never seen that many before.
Established Member
I wouldn't say so - the trails are much too short. It's just a longish exposure of stars.
Established Member
I din't think it was that is why I said "if it is one." If there were that many I would think that would approach storm level.
Established Member
Meteor trails radiate from a central point (more or less). They radiate, and are non-parallel, theoretically meeting again on the opposite side of the sky.
So that the further from the radiant, the fewer trails you see. The 'trails' here are parallel, so the radiant must be 90 degress away in the sky, but think how intense the shower must be there! If only the photographer had turned his camera 90 degrees west - that would have been a sight!
If it was meteors.
Which it wasn't.
John
Established Member
I tend to agree. Too short and too uniform to be a meteor shower.Originally Posted by Jack Higgins
My guess is that it is a photo of star trails that has been misidentified in that paper's stock photo files. With the recent Indian meteorite story, someone has wanted to illustrate their column with a pretty photo and unwisely picked this one.
#-o
Order of Kilopi
Time lapse! Assuming that it is taken in the northern henisphere, it is of the northwest horizon! The pole is outside of the field of view to the upper right. 8)
Vulcan Administrator
If you look closely, you can see a few streaks that aren't parallel to the star streaks, plus they're longer and fainter. That's probably what was being photographed, even if the caption-writer didn't realize it.
Everything I need to know I learned through Googling.
Order of Kilopi
There are three or four meteor trails in the photo, but I think that they are incidental to the intended image of time lapsed star trails.
Established Member
More or less, yeah. Check out the one smack dab in the middle along the left border, and another one about 3/4 the way up on the right side. They do not follow the same path as the rest, and may very well be meteors. Or satellites. Or....
On the other hand, this picture has a pretty good rate of movement on the stars themselves. Compare them to this shot, which I did last night, running my camera for about 30 minutes. Be aware it's a BIG pic (about 2 MB):
http://www.websown.com/~jdonahue/ast...3311267813.jpg
Yeah, see why I didn't post the pic directly?Now, that's about a 30 minute exposure of Mars, with way too much light pollution.
I'm guessing this photographer didn't take that long an exposure, but it WAS time-lapse photography.
I looked up the rate of movement in the book Practical Astrophotography, and on page 39, they talk about how long you can let an exposure go for without getting noticable drift. A star on the celestial equator moves across the sky 1/240 of a degree (15 sec of arc) per second, or 1 second of arc every 1/15 a second of time. Through a 50mm lens, which used to be the standard, you can take up to a 6.8 second exposure without noticable star trails. This is based on "acceptable" image smear being .025mm / 50mm focal length = 1:2000 ratio, and 1 arc second field of view is 1/206265 of the distance from the lens. Divide the 206265 ratio by the acceptable drift angle of 1/200, and you get 102 arc seconds. Then, mutliply that 1/15 of a second mentioned above by 102, and you get roughly 6.8 seconds for your exposure. Use a bigger lens, and you divide by how much its focal length is bigger or smaller it is than that 50 mm camera lens.
Well, that includes everybody's, including my, lesson in optics for the evening. 8-[
Order of Kilopi
Agreed. However, your photo is of Mars, which is very near the celestial equator, where the angular movement is highest. The original photo is of an area closer to the celestial pole, so the trails are shorter for any given exposure time. 8)
Established Member
To isolate meteors from star trails, could one move the camera at the same speed as the earth's rotation, and leave the shutter open?
Order of Kilopi
Yep! The purpose of a clock driven equatorial mount is to track with the stars, so they appear to be nice round points, rather than streaks!
Order of Kilopi
Kaptain K and To Seek saw them and so did I right away. If you've seen time lapse pics of meteors you would know to look for the streaks that are not parallel to the star tracks. There are at least 4. That's a pretty good shower considering.
But I wonder if the news folks who printed it and wrote the caption knew what they were seeing or also thought the star tracks were the objects being pictured? What do you suppose?
Order of Kilopi
Wouldn't the meteor tracks be too faint against the relatively over exposed stars? I've never seen any one take fotos of meteors with that method.
Anyone have any samples?
Order of Kilopi
No no no... That's what many meteor fotos look like. There would only be one stray meteor trail, 2 at the most, unless the meteor shower was the object of the foto.
Established Member
No samples here, but I don't see why that wouldn't work. Even for really long exposures, the light from the stars wouldn't really be badly overexposed, and you'll pick up a lot of stuff you couldn't normally see. The key problem would be light off the moon, I think, interfering with the shot.Wouldn't the meteor tracks be too faint against the relatively over exposed stars? I've never seen any one take fotos of meteors with that method.
Anyone have any samples?
Order of Kilopi
beskeptical,
If it was a meteor shower, the streaks would have a common radiant. Those streaks are randomly oriented, indicating that they were sporadic not shower meteors. Sporadic meteors average 10-12/hr, so 4 in a time exposure is not out of the question. 8)
Order of Kilopi
Either method will get photos of meteors. It is mostly a matter of esthetics. Google: leonids shower photos and you will get over 4700 hits. some are fixed, some are tracked.Wouldn't the meteor tracks be too faint against the relatively over exposed stars? I've never seen any one take fotos of meteors with that method.
Anyone have any samples?
Honored Member
Everything else aside, the streaks are not only parallel, they are all the same length. What are the odds of that if they were meteors? AGN, KapK, JackK and the others are all on the money. Star Tracks.
(The next generation?)
Order of Kilopi
Here's a nice sample:Wouldn't the meteor tracks be too faint against the relatively over exposed stars? I've never seen any one take fotos of meteors with that method.
Anyone have any samples?
http://bicomnet.com/ritchieobs/graphics/leo2001.jpg
It's a nice 2001 Leonid passing through Orion's "shoulders".
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