APOD Challenge

What caused this ring of colors? At the time of this writing, MIT
Physics Professor Walter Lewin had yet to find someone who can give the
correct explanation. Not students. Not colleagues.

See image and details at

http://antwrp.gsfc.nasa.gov/apod/ap040913.html

--
Tom Rankin - Programmer by day, amateur astronomer by night!
Mid-Hudson Astronomy Association - http://mhaa.whodeanie.com
Views and Brews - http://viewsandbrews.com

When replying, remove the capital letters from my email address.

Tom Rankin:
What caused this ring of colors? At the time of this writing, MIT
Physics Professor Walter Lewin had yet to find someone who can give the
correct explanation. Not students. Not colleagues.

See image and details at

http://antwrp.gsfc.nasa.gov/apod/ap040913.html

That's too easy. There was a giant alien behind Professor Lewin with a
very large, very cheap magnifying glass. Just after Prof. Lewin snapped
the photo he burned to a crisp, just as mean children have been known
to burn ants with a glass. Served him right; I have no doubt that the
Professor did this to ants when he was a child; perhaps even as an
adult.

Davoud

--
usenet *at* davidillig dawt com

Tom Rankin wrote
What caused this ring of colors? At the time of this writing, MIT
Physics Professor Walter Lewin had yet to find someone who can give the
correct explanation. Not students. Not colleagues.

See image and details at

http://antwrp.gsfc.nasa.gov/apod/ap040913.html

Well, in the hope that someone will put me straight if I'm wrong,
I'd say it's a Glory, probably man-made rather than naturally occurring,
possibly caused by sunlight reflected off a surface such as glass, then
though a misted window.... But there's not much to go on :-)
Reference; Tricker (1954?) Published by Mills and Boon

Denis
--
DT
Replace nospam with the antithesis of hills

"DT" wrote in message
...
Tom Rankin wrote
What caused this ring of colors? At the time of this writing, MIT
Physics Professor Walter Lewin had yet to find someone who can give
the
correct explanation. Not students. Not colleagues.

See image and details at

http://antwrp.gsfc.nasa.gov/apod/ap040913.html

Well, in the hope that someone will put me straight if I'm wrong,
I'd say it's a Glory, probably man-made rather than naturally
occurring,
possibly caused by sunlight reflected off a surface such as glass,
then
though a misted window.... But there's not much to go on :-)
Reference; Tricker (1954?) Published by Mills and Boon

Denis
--
DT
Replace nospam with the antithesis of hills

I'm pretty certain this is a rainbow caused by microbeads of glass
spilled on the floor. The beads are used to give high-reflection coating
to signs etc, and if scattered on the floor give a highly reflective
effect in the centre and a rainbow effect around the edge. The angle of
the rainbow defines a cone with its apex at the observer's eye - whereas
raindrops give a 42 degree radius to the cone, the higher refractive
index of glass gives a tighter (smaller angle) cone.

I've seen somewhere that the colours in a glory (red inside) are
reversed compared to a rainbow (red outside) - the APOD image
corresponds to the rainbow colours.

But man, that photographer had a funny shaped head!

OG wrote:

But man, that photographer had a funny shaped head!


Yes, he sure does. You may recongise him better in this photo:

http://tinyurl.com/66toj

OG wrote

"DT" wrote in message
...
Tom Rankin wrote
What caused this ring of colors? At the time of this writing, MIT
Physics Professor Walter Lewin had yet to find someone who can give
the
correct explanation. Not students. Not colleagues.

See image and details at

http://antwrp.gsfc.nasa.gov/apod/ap040913.html

Well, in the hope that someone will put me straight if I'm wrong,
I'd say it's a Glory, probably man-made rather than naturally
occurring,
possibly caused by sunlight reflected off a surface such as glass,
then
though a misted window.... But there's not much to go on :-)
Reference; Tricker (1954?) Published by Mills and Boon

Denis
--
DT
Replace nospam with the antithesis of hills

I'm pretty certain this is a rainbow caused by microbeads of glass
spilled on the floor. The beads are used to give high-reflection coating
to signs etc, and if scattered on the floor give a highly reflective
effect in the centre and a rainbow effect around the edge. The angle of
the rainbow defines a cone with its apex at the observer's eye - whereas
raindrops give a 42 degree radius to the cone, the higher refractive
index of glass gives a tighter (smaller angle) cone.

I've seen somewhere that the colours in a glory (red inside) are
reversed compared to a rainbow (red outside) - the APOD image
corresponds to the rainbow colours.

But man, that photographer had a funny shaped head!

I think your idea of the glass beads is a good bet, as I couldn't guess
what the surface he photographed was.
The trouble is that with the diffracting/dispersing medium in front of
the photographer, I would be expecting blue on the outside and red
inside. (I thought Glory and Rainbow colours were the same orientation).
So I'm going to do some reading and not rely on memory!

Denis
--
DT
Replace nospam with the antithesis of hills

I'm pretty certain this is a rainbow caused by microbeads of glass
spilled on the floor.


I think you're right. I've seen this effect before once when a crosswalk
was freshly repainted. Those glass beads are slippery too!

-Florian

On Mon, 13 Sep 2004 06:59:43 -0500, Tom Rankin wrote
(in article ):

What caused this ring of colors? At the time of this writing, MIT
Physics Professor Walter Lewin had yet to find someone who can give the
correct explanation. Not students. Not colleagues.

See image and details at

http://antwrp.gsfc.nasa.gov/apod/ap040913.html

It is called (by some) the Glory, it is caused by sunlight coming from
directly behind the person and shining on fog or mist. The water droplets in
the air act as a prism breaking up the white light into a spectrum.

--
Harry F. Leopold
aa #2076
AA/Vet #4
The Prints of Darkness
(remove gene to email)

³Hey, you are the evolving one not

"Harry F. Leopold" wrote in message
. cox.net...
On Mon, 13 Sep 2004 06:59:43 -0500, Tom Rankin wrote
(in article ):

What caused this ring of colors? At the time of this writing, MIT
Physics Professor Walter Lewin had yet to find someone who can give
the
correct explanation. Not students. Not colleagues.

See image and details at

http://antwrp.gsfc.nasa.gov/apod/ap040913.html

It is called (by some) the Glory, it is caused by sunlight coming from
directly behind the person and shining on fog or mist. The water
droplets in
the air act as a prism breaking up the white light into a spectrum.
It is a fairly common sight, from aircraft flying over clouds, or if you
stand on a mountain top, where the cloud or a mist is below you. In either
case, you can get your shadow, with the ring round it as shown. The
version depicted is unusual, because the mist is close, so the shadow is
large compared to the ring. I'd be suspicious that there was some nearby
equipment creating the mist (perhaps something like a pressure washer).

Best Wishes

On Wed, 15 Sep 2004 07:57:54 -0500, Roger Hamlett wrote
(in article ):

Sorry about the other post, I hit "send" accidently.

"Harry F. Leopold" wrote in message
. cox.net...
On Mon, 13 Sep 2004 06:59:43 -0500, Tom Rankin wrote
(in article ):

What caused this ring of colors? At the time of this writing, MIT
Physics Professor Walter Lewin had yet to find someone who can give
the correct explanation. Not students. Not colleagues.

See image and details at

http://antwrp.gsfc.nasa.gov/apod/ap040913.html

It is called (by some) the Glory, it is caused by sunlight coming from
directly behind the person and shining on fog or mist. The water
droplets in
the air act as a prism breaking up the white light into a spectrum.

It is a fairly common sight, from aircraft flying over clouds, or if you
stand on a mountain top, where the cloud or a mist is below you.

Yup, and they are beautiful from a plane, I haven't seen one (yet) from a
mountain, I hope to someday.

In either
case, you can get your shadow, with the ring round it as shown. The
version depicted is unusual, because the mist is close, so the shadow is
large compared to the ring. I'd be suspicious that there was some nearby
equipment creating the mist (perhaps something like a pressure washer).

Looks like that is how it was made, I agree. I saw one very much like it from
the bow of a ship once, the sun was just right as we hit a wave and there it
was, spectacular!
--
Harry F. Leopold
aa #2076
AA/Vet #4
The Prints of Darkness
(remove gene to email)

³The universe is bigger than me. It doesn't care about me. That's fine --
because I care about me. I'd like to continue to do the things I do, and to
do other things as well. So these things will eventually end. It still
matters to me that they happen.

The realization that life belongs to me, and not to some god or some
minister, and that I could decide what to make of it -- that was a truly
liberating moment for me.³-Eyelessgame