APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

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APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by APOD Robot » Tue Jul 28, 2015 4:11 am

Image Rainbows and Rays over Bryce Canyon

Explanation: What's happening over Bryce Canyon? Two different optical effects that were captured in one image taken earlier this month. Both effects needed to have the Sun situated directly behind the photographer. The nearest apparition was the common rainbow, created by sunlight streaming from the setting sun over the head of the photographer, and scattering from raindrops in front of the canyon. If you look closely, even a second rainbow appears above the first. More rare, and perhaps more striking, are the rays of light that emanate out from the horizon above the canyon. These are known as anticrepuscular rays and result from sunlight streaming though breaks in the clouds, around the sky, and converging at the point 180 degrees around from the Sun. Geometrically, this antisolar point must coincide with the exact center of the rainbows. Located in Utah, USA, Bryce Canyon itself contains a picturesque array of ancient sedimentary rock spires known as hoodoos.

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by Sternfreund » Tue Jul 28, 2015 4:28 am

Great photo but could you explain why (when the phenomenon happens only if the sun comes from behind) the shadows on the right side of the picture implicate that the sun comes from the right?

the old blind man

Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by the old blind man » Tue Jul 28, 2015 4:42 am

Sternfreund wrote:Great photo but could you explain why (when the phenomenon happens only if the sun comes from behind) the shadows on the right side of the picture implicate that the sun comes from the right?
Obviously, the pictures were taken in the same studio they used to film Capricorn One and the other 6 features. :mrgreen:

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by geckzilla » Tue Jul 28, 2015 4:45 am

Sternfreund wrote:Great photo but could you explain why (when the phenomenon happens only if the sun comes from behind) the shadows on the right side of the picture implicate that the sun comes from the right?
That's an illusion. If you look at the little shadows the pebbles cast, they're following the same vanishing point.
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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by Chris Peterson » Tue Jul 28, 2015 4:52 am

Sternfreund wrote:Great photo but could you explain why (when the phenomenon happens only if the sun comes from behind) the shadows on the right side of the picture implicate that the sun comes from the right?
You're being fooled by two things: the extreme wide angle of the shot (the rainbow is ~84° wide at the base), and the uneven ground. These things tend to hide the direction of the Sun. You need to look for a common vanishing point, not for obviously parallel shadows.
Chris

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by alter-ego » Tue Jul 28, 2015 5:07 am

Chris Peterson wrote:
Sternfreund wrote:Great photo but could you explain why (when the phenomenon happens only if the sun comes from behind) the shadows on the right side of the picture implicate that the sun comes from the right?
You're being fooled by two things: the extreme wide angle of the shot (the rainbow is ~84° wide at the base), and the uneven ground. These things tend to hide the direction of the Sun. You need to look for a common vanishing point, not for obviously parallel shadows.
Yup. It's an illusion that the shadows are directed leftward. If you look closely at the small rocks at the lower right of the image you'll see their shadows are properly toward the antisolar point (nominal so considering any field curvature effect changing its direction a little). I'd say you're seeing other shadows, possibly the horizontal timbers that appear to make up a fence line around the area and likely behind the photographer's position.

Edit: View John's second picture (Brice Canyon III) at his link
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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by Sternfreund » Tue Jul 28, 2015 8:18 am

Thanks for the explanation! :)

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by geckzilla » Tue Jul 28, 2015 9:20 am

It took three of us, but we did it.
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tetrodehead

Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by tetrodehead » Tue Jul 28, 2015 9:38 am

Great eye candy.
Shortly after sunset, would the vanishing point be in the sky?
Anyone got pics?

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by NGC3314 » Tue Jul 28, 2015 1:16 pm

tetrodehead wrote:Shortly after sunset, would the vanishing point be in the sky?
Anyone got pics?
Closest I can come is this 1981 shot of the shadow of Mt. Lemmon, Arizona, being cast on the open atmosphere just before sunrise. The summit altitude (close to 3000 meters) give the rising sun enough dip below the usual horizon to have a shadow vanishing point well above the horizon.
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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by darksky2500@gmail.com » Tue Jul 28, 2015 1:33 pm

Hi all, I'm the photographer of the Bryce Canyon image. Thanks to those who provided the explanation regarding the extreme wide angle and possible confusing shadow-play. Also, in answer to a question about anticrepuscular shots with the sun below the horizon, if you search google images for the words "anti crepuscular," the first page of images will contain several examples.

StareDecisis

Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by StareDecisis » Tue Jul 28, 2015 4:17 pm

"Both effects needed to have the Sun situated directly behind the photographer."

Uh, both effects ALWAYS occur so that each observer sees them exactly opposite the sun. Another guy 5 feet to the left sees a different rainbow and a different set of anticrepuscular rays.

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by darksky2500@gmail.com » Tue Jul 28, 2015 5:25 pm

Definitely true about the rainbow. Not so sure about the anticrepuscular rays...
StareDecisis wrote: Uh, both effects ALWAYS occur so that each observer sees them exactly opposite the sun. Another guy 5 feet to the left sees a different rainbow and a different set of anticrepuscular rays.

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by Chris Peterson » Tue Jul 28, 2015 5:36 pm

darksky2500 wrote:Definitely true about the rainbow. Not so sure about the anticrepuscular rays...
StareDecisis wrote: Uh, both effects ALWAYS occur so that each observer sees them exactly opposite the sun. Another guy 5 feet to the left sees a different rainbow and a different set of anticrepuscular rays.
The center of the rainbow and the vanishing point of anticrepuscular rays will always be at the antisolar point, which is different for each observer. Every observer sees a different rainbow in the sense that the light rays reaching their eyes have taken a completely different path, through a different set of raindrops. But every observer sees the same anticrepuscular rays, which are just shadows. Two close observers see the same shadows, just from very slightly different viewpoints. To say they are seeing a different set of rays is like saying two people looking at a tree are seeing different trees just because their view is different.
Chris

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by Steve Dutch » Tue Jul 28, 2015 5:40 pm

I seriously envy the photographer. I saw something like this once, and only once, and did not have a camera with me, alas (pre-cell phone camera era).

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by BMAONE23 » Tue Jul 28, 2015 7:05 pm

Steve Dutch wrote:I seriously envy the photographer. I saw something like this once, and only once, and did not have a camera with me, alas (pre-cell phone camera era).
Back in the day when all cell phones were stamped MOTOROLA?

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by quigley » Tue Jul 28, 2015 9:41 pm

What a great photo. I hope to see anticrepuscular rays someday in my lifetime. I'm always looking for them.

As a side note, is there a NASA site that posts regular info and photos of Pluto and the New Horizons mission?

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by Ron-Astro Pharmacist » Tue Jul 28, 2015 10:10 pm

"We calculate it was from back in the 20th century."
fossil_phone.jpg
"I wonder how it ended up in the mud?"
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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by MarkBour » Tue Jul 28, 2015 10:37 pm

Chris Peterson wrote:
darksky2500 wrote:Definitely true about the rainbow. Not so sure about the anticrepuscular rays...
StareDecisis wrote: Uh, both effects ALWAYS occur so that each observer sees them exactly opposite the sun. Another guy 5 feet to the left sees a different rainbow and a different set of anticrepuscular rays.
The center of the rainbow and the vanishing point of anticrepuscular rays will always be at the antisolar point, which is different for each observer. Every observer sees a different rainbow in the sense that the light rays reaching their eyes have taken a completely different path, through a different set of raindrops. But every observer sees the same anticrepuscular rays, which are just shadows. Two close observers see the same shadows, just from very slightly different viewpoints. To say they are seeing a different set of rays is like saying two people looking at a tree are seeing different trees just because their view is different.
Anticrepuscular rays are totally new to me, I've never seen them and this photo is very nice. I have to agree with Chris. If this is all true, then, as a result, if you saw this scene and were in a very fast vehicle moving perpendicular to the direction of the camera, You would see the rainbow magically moving with you, which I'm familiar with, but the rays, which have to stay pointed to the almost invariant vanishing point must rotate around it as you move. If you were moving to the right, they would rotate counter-clockwise. Does that sound correct? I'd love to see it some time.
Mark Goldfain

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by geckzilla » Tue Jul 28, 2015 10:59 pm

MarkBour wrote:Anticrepuscular rays are totally new to me, I've never seen them and this photo is very nice. I have to agree with Chris. If this is all true, then, as a result, if you saw this scene and were in a very fast vehicle moving perpendicular to the direction of the camera, You would see the rainbow magically moving with you, which I'm familiar with, but the rays, which have to stay pointed to the almost invariant vanishing point must rotate around it as you move. If you were moving to the right, they would rotate counter-clockwise. Does that sound correct? I'd love to see it some time.
If volumetric rendering wasn't such a processor-intensive pain in the butt, it would be easy to make a 3d scene and simulate this sort of view.
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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by Boomer12k » Wed Jul 29, 2015 12:31 am

WOW....that is just AWESOME!!!!!

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by LocalColor » Wed Jul 29, 2015 2:04 am

Bryce Canyon is a beautiful place and the photographer was in the right place at the right time. Contrats! Makes a great APOD, a stunning view combined with science on our planet. :)

NoseyNick

Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by NoseyNick » Wed Jul 29, 2015 3:11 am

Nobody said "So Intense!" or "What does this MEAN?" yet? I'm disappointed in you all ;-)

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by dawson » Wed Jul 29, 2015 3:55 pm

quigley wrote:As a side note, is there a NASA site that posts regular info and photos of Pluto and the New Horizons mission?
you'll find them and a lot more here http://www.nasa.gov/multimedia/imagegallery/index.html

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Re: APOD: Rainbows and Rays over Bryce Canyon (2015 Jul 28)

Post by bystander » Wed Jul 29, 2015 5:05 pm

quigley wrote: As a side note, is there a NASA site that posts regular info and photos of Pluto and the New Horizons mission?

http://www.nasa.gov/newhorizons
http://pluto.jhuapl.edu/
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