APOD: Anticrepuscular Rays Converge the... (2019 Jun 24)

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APOD Robot
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APOD: Anticrepuscular Rays Converge the... (2019 Jun 24)

Post by APOD Robot » Mon Jun 24, 2019 4:10 am

Image Anticrepuscular Rays Converge Opposite the Sun

Explanation: Is there ever anything interesting to see in the direction opposite the Sun? Sometimes there is. Notable items include your own shadow, a shadow of the Moon during a total solar eclipse, a full moon -- in eclipse if the alignment's good enough, a full earth, planets at opposition, glints from planets, the gegenschein from interplanetary dust, the center of a rainbow, hall-of-mountain fogbows, an airplane glory, and something yet again different if your timing, clouds and Sun position are just right. This different effect starts with clouds near the Sun that are causing common crepuscular rays to stream though. In the featured rare image taken from an airplane in mid-April, these beams were caught converging 180 degrees around, on the opposite side of the sky from the Sun, where they are called anticrepuscular rays. Therefore, it may look like something bright is shining at the antisolar point near the image center, but actually it is reverse-shining because, from your direction, light is streaming in, not out.

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heehaw

Re: APOD: Anticrepuscular Rays Converge the... (2019 Jun 24)

Post by heehaw » Mon Jun 24, 2019 9:13 am

TODAY we celebrate Anticrepuscular Rays Day: https://epod.usra.edu/blog/

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orin stepanek
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Re: APOD: Anticrepuscular Rays Converge the... (2019 Jun 24)

Post by orin stepanek » Mon Jun 24, 2019 11:44 am

Looks like an underwater shot! :shock:
Orin

Smile today; tomorrow's another day!

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Re: APOD: Anticrepuscular Rays Converge the... (2019 Jun 24)

Post by vstill » Mon Jun 24, 2019 1:09 pm

"…clouds near the Sun…"

This phrase needs more explanation, because it makes no sense otherwise.

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Chris Peterson
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Re: APOD: Anticrepuscular Rays Converge the... (2019 Jun 24)

Post by Chris Peterson » Mon Jun 24, 2019 1:12 pm

vstill wrote:
Mon Jun 24, 2019 1:09 pm
"…clouds near the Sun…"

This phrase needs more explanation, because it makes no sense otherwise.
I don't think it takes a whole lot of effort to understand what this means, unless you don't know where clouds form. (Hint: it's not in interplanetary space.)
Chris

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MarkBour
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Re: APOD: Anticrepuscular Rays Converge the... (2019 Jun 24)

Post by MarkBour » Mon Jun 24, 2019 5:24 pm

Chris Peterson wrote:
Mon Jun 24, 2019 1:12 pm
vstill wrote:
Mon Jun 24, 2019 1:09 pm
"…clouds near the Sun…"

This phrase needs more explanation, because it makes no sense otherwise.
I don't think it takes a whole lot of effort to understand what this means, unless you don't know where clouds form. (Hint: it's not in interplanetary space.)
One of the natural and common conventions in astronomy is to refer to things as "near each other", when they are -- from the observer's viewpoint -- near each other in the 2-dimensional projection of the sky onto the observer's eyes. Is that a sufficient explanation here? The clouds being referred to are near the solar position in the sky. The image for today, is taken looking directly opposite of that point in the sky, toward the anti-solar point. This can only be done when the sun is right near the horizon ... unless you have a lake or something to look at.
Mark Goldfain

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Re: APOD: Anticrepuscular Rays Converge the... (2019 Jun 24)

Post by Boomer12k » Tue Jun 25, 2019 3:04 am

Interesting phenomenon... I get a bit claustrophobic looking at the lower part of the image...the analogy of being "shot under water"...is a good one for me...

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m.p.

Re: APOD: Anticrepuscular Rays Converge the... (2019 Jun 24)

Post by m.p. » Tue Jun 25, 2019 6:05 am

... because, from your direction, light is streaming in, not out.

More precisely: every light captured on a photography is light reflected on objects clouds and particles and it must be light streamed towards you :-)