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MongotheGreat
2002-Jan-16, 08:17 AM
I ran across this incredible picture. I can't remember where I got it. It wasn't taken by me. The guy I got it from called it "The Spacefly".
http://php.indiana.edu/~mwimmer/spacefly.jpg

It doesn't take long to figure out what it is, but it is incredible to look at. It's wierd that it's not perfectly symetrical.
Try to imagine the function that would predict that shape. How many internal reflections do you think it took to form that image?

Mongo

steinhenge
2002-Jan-16, 09:32 AM
It doesn't take long to figure out what it is, but it is incredible to look at.

As I'm not one of the brightest bulbs in the pantry, why don't you just saddle on over here and tell pappy just what that is.

I thank you in advance.

MongotheGreat
2002-Jan-16, 09:40 AM
Absolutely. The image is caused by internal reflections inside the telescope used to take the picture. That is, light that didn't follow the intended path to the focal plain, but for some reason, took another path and formed the complex image.
Mongo

John Kierein
2002-Jan-16, 12:44 PM
That's what a lot of UFO photos are.

ToSeek
2002-Jan-16, 01:19 PM
On 2002-01-16 07:44, John Kierein wrote:
That's what a lot of UFO photos are.


Yep, that's right. I think the photo really depicts what happens when one of the little gray aliens activates their hyperdrive while still in Earth's atmosphere. Get me a couple more photos - I'll write a book, appear on talk shows, and make millions!

/phpBB/images/smiles/icon_wink.gif

MongotheGreat
2002-Jan-16, 04:38 PM
C'mon now, I didn't start his thread as a joke for conspiracy theorists. I just wanted to know what you all thought about this intriguing phenomen. It does kind of look like a fly though, dudnit? A space fly.

Mongo(Space Fly)theGreat
Now that would be a magnificent monicker(sic).

Donnie B.
2002-Jan-16, 04:43 PM
It looks to me like a fake, where someone superimposed a picture of a deep-sea jelly on a background of stars.

If it truly is formed by internal reflections, I'm impressed... there must be a very interesting structure of lenses involved. Perhaps multicoated optics? I don't know enough about modern astronomical optics to guess...

The Bad Astronomer
2002-Jan-16, 05:55 PM
One reason the image is so complicated is that the optics used in the image weren't perfectly aligned. Look at the bright star: it isn't in the center of the reflected glow. So the squiggly internal reflection might look more like standard lens flares if the optics had been collimated (aligned) better.

Having said that... it's a way cool image. /phpBB/images/smiles/icon_wink.gif

Chip
2002-Jan-16, 06:11 PM
On 2002-01-16 03:17, MongotheGreat wrote:
I ran across this incredible picture. I can't remember where I got it. It wasn't taken by me. The guy I got it from called it "The Spacefly".
http://php.indiana.edu/~mwimmer/spacefly.jpg


At the apex of the "cone" there appears to be a "little" bright star. Is that the source of the light bouncing around the lenses resulting in the "spacefly" structure? Or is the light mostly from the uncollimated bright central star? Just curious.

MongotheGreat
2002-Jan-16, 06:18 PM
I got this picture from some guys amateur astronomy page, however I lost the link. I have seen other types of artifacts like this, but none as seemingly complex. I believe he was using a Schmidt camera, they have pretty complex lenses and mirrors.
I might try to find other types of these artifacts and post them. /phpBB/images/smiles/icon_smile.gif

Mongo

steinhenge
2002-Jan-16, 10:24 PM
On 2002-01-16 04:40, MongotheGreat wrote:
Absolutely. The image is caused by internal reflections inside the telescope used to take the picture. That is, light that didn't follow the intended path to the focal plain, but for some reason, took another path and formed the complex image.
Mongo


Thank you Mongo. That is very cool indeed, and being only the most amateur of astronomers, I never would have guessed that.

Just out of curiosity, does this sort of fake (though pretty) image occur with any sort of frequency in professional astronomy? If so, it must be quite a pain.

MongotheGreat
2002-Jan-16, 10:48 PM
Like the BA said, this only occurs if there is some flaw in the optics such as being out of alignment. Professional astronomers take great care to make sure there is proper alignment.

Mongo

The Bad Astronomer
2002-Jan-17, 02:53 AM
...and even so you can get internal reflections. We had them on STIS (on Hubble), and they did play havoc with some observations of bright stars. There are ways to try to make them less of a pain, but that translates into very expensive optics.

steinhenge
2002-Jan-17, 05:52 AM
...and speaking of the Hubble, I'm in love with this image:

http://oposite.stsci.edu/pubinfo/pr/1998/14/content/9814a1.jpg

When the Hubble was launched and we quickly found out that it had problems and seemed unable to "work", as such (please excuse all the technical jargon... and yes, this is sarcasm), did it just show blurred images or were there any interesting illusions like the one above. Or perhaps something different altogether?

DStahl
2002-Jan-17, 06:58 AM
steinhenge, that pic often appears on my screen as wallpaper. I love it too.

What I know about optics would half-fill a thimble, but the optical artifact in the jpg is strikingly similar to some of the graphics produced by one of Stephen Ferguson's fractal or strange attractor programs. I wonder if the light path that produce the artifact has some mathematical link to the functions used in Ferguson's program? Intriguing.

--Don Stahl

<font size=-1>[ This Message was edited by: DStahl on 2002-01-17 02:00 ]</font>

ToSeek
2002-Jan-17, 03:20 PM
Speaking of which, doesn't this "UFO" (http://www.rense.com/general19/new.htm) look like some kind of spherical aberration?

_________________
"... to strive, to seek, to find, and not to yield." - Tennyson, Ulysses

<font size=-1>[ This Message was edited by: ToSeek on 2002-01-17 10:20 ]</font>

The Bad Astronomer
2002-Jan-17, 04:23 PM
A lot of UFO footage is actually badly focused mundane things like stars, Venus and airplanes. A big tip-off: video footage stars off on wide angle, then when they zoom in the "UFO" gets resolved into a disk or weirdly patterned shape, it's because of focussing effects. Video cameras have a hard time maintaining focus when you zoom quickly (try it on a relatively nearby object like a person a few meters away). A bright point source like a distant airplane or bright star/planet will very quickly become a blurred disk when this happens.

Russ
2002-Jan-18, 05:13 PM
Are you sure this is stray light. It looks to me more like somebody triped over a tripod leg causing vibrations. Take a 5 minute exposure with 3 seconds of vibration you could get something like this.

The reason I suggest this is, I've tripped over a guys tripod. /phpBB/images/smiles/icon_redface.gif He showed me the exposure and it wasn't terribly different from your pic.

MongotheGreat
2002-Jan-19, 06:15 AM
Internal reflection was the reason given by the photographer, I'm sure he would have noted if there was a significant vibration. I just don't see how a vibration or kick could have formed the spacefly while leaving the other stars, especially the bright one, clear.
Mongo