APOD: The Belt of Venus Over Mercedes... (2012 Feb 07)

[APOD Robot]

The Belt of Venus Over Mercedes Argentina

Explanation: Although you've surely seen it, you might not have noticed it. During a cloudless twilight, just before sunrise or after sunset, part of the atmosphere above the horizon appears slightly off-color, slightly pink or orange. Called the Belt of Venus, this off-color band between the dark eclipsed sky and the blue sky can be seen in nearly every direction including that opposite the Sun. Straight above, blue sky is normal sunlight reflecting off the atmosphere. In the Belt of Venus, however, the atmosphere reflects light from the setting (or rising) Sun which appears more red. Below the Belt of Venus, the atmosphere appears more dark because no sunlight reaches it. The Belt of Venus can be seen from any location with a clear horizon. Pictured above last month over Mercedes, Argentina, a panoramic vista featuring the Belt of Venus was digitally stitched together from 16 smaller images. The belt is frequently caught by accident in other photographs.

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[Ann]

Congratulations, Luis Argerich! That's a lovely image of the pink Belt of Venus and the dark blue Earth shadow below it. Judging from how the crescent Moon at far right is illuminated in this image (it is illuminated on its left side), the image seems to be taken in the morning, and the dark blue Earth shadow is sinking as the Sun is rising.

What a great picture!

Ann

[Flase]

Judging from how the crescent Moon at far right is illuminated in this image (it is illuminated on its left side), the image seems to be taken in the morning, and the dark blue Earth shadow is sinking as the Sun is rising.

Hahaa! You're wrong! Argentina is in the southern hemisphere where everything is upside down. Water spins around a plug-hole backwards, people walk upside down and the Sun and Moon appear towards the North, seeming to move backwards...

[Flase]

More about the antipodes...
http://skyvington.blogspot.co.nz/2007/05/upside-down-world.html
I'm not sure about the bit about buffoons resigning, though. That's a little bit hopeful.

[Ann]

Judging from how the crescent Moon at far right is illuminated in this image (it is illuminated on its left side), the image seems to be taken in the morning, and the dark blue Earth shadow is sinking as the Sun is rising.

Hahaa! You're wrong! Argentina is in the southern hemisphere where everything is upside down. Water spins around a plug-hole backwards, people walk upside down and the Sun and Moon appear towards the North, seeming to move backwards...

Ooops! My mistake. So it's sunset, then, and the Earth shadow is rising.

Ann

[Beyond]

And so is Ann

[Ann]

And so is Ann

Right. Truth to tell, I wouldn't mind going back to bed right now.

(Sorry for veering off topic.)

Ann

[Flase]

Don't worry. Town planners and architects in the northern hemisphere always got that wrong. There are stately homes in New Zealand where the homeowners' rooms faced South and are therefore cold, whereas the servants' areas faced the Sun to the North...

[metleif]

The crescent Moon at far right shouldn't be far from the Sun. But where is the Sun..?
To me, it looks as if the right part of the picture was taken nearly opposite the Sun, as Earth's shadow here is very pronounced. But this does not match the Moon's appearance.
Hard to decide, however ..

[Laurent Laveder]

You're right Metleif, the Crescent indicates the position of the Sun, bellow on the left of the Moon. So the Belt of Venus isn't in the right position. It should be at the opposite horizon. The only time the Moon is near the Belt of Venus is during Full Moon.
Here are some examples:

(details http://www.pixheaven.net/photo_us.php?nom=dcp_9853-55)


(details http://www.pixheaven.net/photo_us.php?nom=0507200013)

So why is the Crescent Moon beside the Belt of Venus? I don't know! Regards.

[luigi]

Hi,

I'm really honored and happy to see my photo as an APOD.

I've seen the belt of Venus many times but this day it was really eye catching. Maybe it is related to the presence of volcanic ashes still in the atmosphere from the chilean volcano.
I was surprised to see the shadow of earth with the naked eye because this is not a high location. I've seen the shadow in many mountain photos but I was never able to see it so clearly from the plains.

Sometimes the sky is just special.

About direction the belt of Venus covered almost the entire 360 degrees horizon Visually. I stopped the panorama to avoid a road and some electricity poles but I could've taken the whole 360 belt. Maybe I still should have done it.

Thanks!

[neufer]

Judging from how the crescent Moon at far right is illuminated in this image (it is illuminated on its left side), the image seems to be taken in the morning, and the dark blue Earth shadow is sinking as the Sun is rising.

Hahaa! You're wrong! Argentina is in the southern hemisphere where everything is upside down. Water spins around a plug-hole backwards, people walk upside down and the Sun and Moon appear towards the North, seeming to move backwards...

Yugoslavia "Belt of Venus" Flag

Paraguay "Belt of Venus" Flag

[Redbone]

Judging from how the crescent Moon at far right is illuminated in this image (it is illuminated on its left side), the image seems to be taken in the morning, and the dark blue Earth shadow is sinking as the Sun is rising.

Hahaa! You're wrong! Argentina is in the southern hemisphere where everything is upside down. Water spins around a plug-hole backwards, people walk upside down and the Sun and Moon appear towards the North, seeming to move backwards...

This is, of course, wrong, and Ann is correct, it is morning. The full Moon always rises at sunset, the new Moon always rises at sunrise. This being a few days before the new moon, it is rising just before sunrise.

[luigi]

Judging from how the crescent Moon at far right is illuminated in this image (it is illuminated on its left side), the image seems to be taken in the morning, and the dark blue Earth shadow is sinking as the Sun is rising.

Hahaa! You're wrong! Argentina is in the southern hemisphere where everything is upside down. Water spins around a plug-hole backwards, people walk upside down and the Sun and Moon appear towards the North, seeming to move backwards...

This is, of course, wrong, and Ann is correct, it is morning. The full Moon always rises at sunset, the new Moon always rises at sunrise. This being a few days before the new moon, it is rising just before sunrise.

I'm the Photographer here to clarify.
The shots were taken after sunset.

The moon has a "C" shape in the south hemisphere when it is in crescent phase, in other words becoming a full moon.
We say "C = creciente" in spanish here.

Now I can tell you I didn't touch anything because I don't want to touch anything when I send a photo to APOD. In the photo version at my website I cloned some poles that I thought could be distracting in a big print but I sent the original version with the poles to APOD (don't touch it Luis!)

If the moon is not in the right place then it's something the stitching software did and I didn't notice and I hope it's not a big problem.

[owlice]

Luis, it's a spectacular picture (but you already know I think so)!! I was so pleased to see this as today's APOD!

[Redbone]

I stand corrected! After further thought, indeed the left and right are reversed when looking at the moon from Northern and Southern hemisphers. Learned something new, thanks.

[BMAONE23]

One thing I notice that really stands out to me is the Moon. Everytime I see the moon near the Belt of Venus, it is nearly full and not a crescent moon as is shown in the image. It is also too high above the belt to be eclipsed.
Presumably, the setting sun is off to the left of the image as the Earth Shadow is most apparent to the right which places the crescent moon as rising near the belt

[drollere]

this is a very familiar effect to landscape painters (such as myself). in transparent watercolors and glazed oil paints, it raises the tricky problem of painting the transition from blue sky to yellow horizon without introducing any obvious green ... which in paints is produced by mixing yellow and blue.

we should also appreciate the splendid visual summation this effect creates of the blackbody spectrum, cool at the horizon to hot in the sky. i believe every hue can be matched by a correlated color temperature. only the cyan or cerulean hues between yellow and blue would be out of place.

this seems pretty obviously a photograph taken at sunset. not only is the crescent moon in the correct reversed position for the southern hemisphere, the density of particulates is rather high for morning air.

[McFrost69]

I'm the Photographer here to clarify.
The shots were taken after sunset.

The moon has a "C" shape in the south hemisphere when it is in crescent phase, in other words becoming a full moon.
We say "C = creciente" in spanish here.

Now I can tell you I didn't touch anything because I don't want to touch anything when I send a photo to APOD. In the photo version at my website I cloned some poles that I thought could be distracting in a big print but I sent the original version with the poles to APOD (don't touch it Luis!)

If the moon is not in the right place then it's something the stitching software did and I didn't notice and I hope it's not a big problem.

Luis;
As a fellow panoramic photographer, I must congratulate you on a stunning example of the Belt of Venus. It is marred only by the position of the crescent moon. I will accept your explanation of a stitching software error, since such things can and do happen when stitching large images. However, it is physically impossible for a cresent moon to appear in the position it does in your panoramic image. I would suggest you submit the un-edited and un-cropped version of your panoramic or even just the frame in which the moon originally appears for examination.

[Chris Peterson]

Luis;
As a fellow panoramic photographer, I must congratulate you on a stunning example of the Belt of Venus. It is marred only by the position of the crescent moon. I will accept your explanation of a stitching software error, since such things can and do happen when stitching large images. However, it is physically impossible for a cresent moon to appear in the position it does in your panoramic image. I would suggest you submit the un-edited and un-cropped version of your panoramic or even just the frame in which the moon originally appears for examination.

I don't believe there is any problem here with respect to the position of the Moon. When the image was made, the Moon was 50° in azimuth north of the Sun. That places the Sun just below the horizon not far from the left edge of the image- where there is no shadow visible. When the conditions are right, I've seen the Belt of Venus circle the horizon, disappearing only very close to the Sun... certainly covering more than 300° of azimuth.

The entire panorama looks like it covers about 80° of azimuth.

[hotdigittydawg]

this is a very familiar effect to landscape painters (such as myself). in transparent watercolors and glazed oil paints, it raises the tricky problem of painting the transition from blue sky to yellow horizon without introducing any obvious green ... which in paints is produced by mixing yellow and blue.

This statement begs the question, 'Why is it we don't see any green in that transition zone between the yellow and the blue?' My guess is the answer would be something like, 'Because the oxygen absorbs that portion of the spectum of visible light and therefore it's not reflected back to our eyes.' Am I close?

[geckzilla]

But there is green there.

[Royal]

I'm surprised that no one has mentioned (maybe I missed it) the old trick of tilting one's head 90 degrees, which seems to accentuate the difference in chromaticity.
I have tried it, even on the photo, and it seems to work. Is it psychological, or it it physiological?

[Ann]

this is a very familiar effect to landscape painters (such as myself). in transparent watercolors and glazed oil paints, it raises the tricky problem of painting the transition from blue sky to yellow horizon without introducing any obvious green ... which in paints is produced by mixing yellow and blue.

This statement begs the question, 'Why is it we don't see any green in that transition zone between the yellow and the blue?' My guess is the answer would be something like, 'Because the oxygen absorbs that portion of the spectum of visible light and therefore it's not reflected back to our eyes.' Am I close?

I think that the answer is that green is a primary color to our eyes, which means that we will only see green if there is a strong peak in the middle of the spectrum. This is obviously not the case with any part of the twilight sky, which is a mixture of many wavelengths.

The reason why green is a primary color to our eyes may have to do with survival. Plants on the Earth are almost always green, and where there is vegetation, there is probably water. Humanity undoubtedly spent hundreds of thousands of years surviving on the savanna, where our ability to detect the green color of plants was of critical importance.

But the sky is never grassy green or leafy green, so we don't see it as green.

Ann

[luigi]

this is a very familiar effect to landscape painters (such as myself). in transparent watercolors and glazed oil paints, it raises the tricky problem of painting the transition from blue sky to yellow horizon without introducing any obvious green ... which in paints is produced by mixing yellow and blue.

This statement begs the question, 'Why is it we don't see any green in that transition zone between the yellow and the blue?' My guess is the answer would be something like, 'Because the oxygen absorbs that portion of the spectum of visible light and therefore it's not reflected back to our eyes.' Am I close?

I think that the answer is that green is a primary color to our eyes, which means that we will only see green if there is a strong peak in the middle of the spectrum. This is obviously not the case with any part of the twilight sky, which is a mixture of many wavelengths.

The reason why green is a primary color to our eyes may have to do with survival. Plants on the Earth are almost always green, and where there is vegetation, there is probably water. Humanity undoubtedly spent hundreds of thousands of years surviving on the savanna, where our ability to detect the green color of plants was of critical importance.

But the sky is never grassy green or leafy green, so we don't see it as green.

Ann

Ann, maybe it's in our genes as I'm fascinated about the idea of green things in the sky.
I've never seen an Aurora but I would love to see one. (someday, someday)
And then there's airglow but I don't think you can see it visually, I have photographed airglow from a really dark location but I don't remember seeing it with my eyes.