APOD: The Belt of Venus over the Valley of... (2010 Apr 04)

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APOD: The Belt of Venus over the Valley of... (2010 Apr 04)

Post by APOD Robot » Sun Apr 04, 2010 4:00 am

Image The Belt of Venus over the Valley of the Moon

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. 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. The Belt of Venus can be seen from any location with a clear horizon. Pictured above, the Belt of Venus was photographed above morning fog in the Valley of the Moon, a famous wine-producing region in northern California, USA. The belt is frequently caught by accident in other photographs.

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Richard Carroll

Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by Richard Carroll » Sun Apr 04, 2010 5:44 am

I prefer the older name, "the Girdle of Venus", simply because it's amusing and shows how words change over time. :)

Scottp88

Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by Scottp88 » Sun Apr 04, 2010 6:48 am

The wording is akward and does not adequately describe the effect. "Normal sunlight," "setting sun" - but the sun has set in the picture so what's the difference?

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Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by neufer » Sun Apr 04, 2010 11:12 am

Richard Carroll wrote:I prefer the older name, "the Girdle of Venus", simply because it's amusing and shows how words change over time. :)
Art Neuendorffer

mpaulson44

Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by mpaulson44 » Sun Apr 04, 2010 2:19 pm

I was disappointed I had to click on two links to find out what I was looking at.
I was expecting something about stars, and got this thing which obviously was on earth.
an explanation with the picture would be nice...

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Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by Chris Peterson » Sun Apr 04, 2010 2:52 pm

Richard Carroll wrote:I prefer the older name, "the Girdle of Venus", simply because it's amusing and shows how words change over time.
It has other names as well. I've always called it nightrise.

I'm not sure that the Girdle of Venus is an older name than the Belt of Venus. Neither is all that old- the term first appeared in the late 1800s, and not in any astronomical literature. In an astronomy text I have from 1888, it is called the antitwilight arch, a term I also find in an astronomy text from 1940.

I don't use either of the "Venus" terms when I discuss the phenomenon, but would especially avoid Girdle of Venus because it is mainly a term associated with palmistry.
Chris

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Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by owlice » Sun Apr 04, 2010 3:50 pm

Chris Peterson wrote:I don't use either of the "Venus" terms when I discuss the phenomenon, but would especially avoid Girdle of Venus because it is mainly a term associated with palmistry.
It appears the phrase figures into the thoughts of some who think a woman's hips are smaller than her head, too. :roll:
Chris Peterson wrote:It has other names as well. I've always called it nightrise.
Oh, I like that! I've thought of it as "shadow rise" since this APOD appeared.
Last edited by owlice on Sun Apr 04, 2010 6:13 pm, edited 1 time in total.
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Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by biddie67 » Sun Apr 04, 2010 5:46 pm

neufer -- I burst out laughing at your bit of historical/hysterical info above - this one is certainly a keeper!!

owlice -- I like the term "shadowrise" also - thanks for the link to the older APOD. As a rather recent discoverer of APOD, I am slowly getting into savoring the older APOD's along with each new daily one.

Coincidentally, there was a heavy fog in my area this morning - I grabbed my camera and headed out to take pictures - unfortunately, none of my pics were as beautiful, peaceful or interesting as today's APOD.

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Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by astrogimp » Sun Apr 04, 2010 8:11 pm

If you are in the mountains the "Belt of Venus" is more commonly referred to as "alpenglow" and can turn both the low lying atmosphere and snow covered mountains opposite the sun pink; sometimes bright pink. As an aside, the is a great old book "Sunsets, twilights, and evening skies" by Meinel and Meinel that describes such phenomena (although neither the terms Belt of Venus or alpenglow are referred to in the book).

astrix

Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by astrix » Sun Apr 04, 2010 8:46 pm

why does no one seem to call a spade a spade? the blue is earth's shadow. the red on top of it is the sunlight refracted by earth's atmosphere; it is what gives the redness in the clouds at sunset/sunrise (and to the fully eclipsed moon). the rise of the shadow at sunset of the blue shadow is what i see as proof of sun has set, it starts out dark as we are looking along the dge of the shadow contrasted to the fading daylight, but it becomes more edifuse later as night comes on as we no longer see the shadow edge on...

frankly. i see no relationship to venus(? )

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Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by markk » Sun Apr 04, 2010 10:22 pm

astrix wrote:frankly. i see no relationship to venus(? )
I would guess that the relationship is that both are visible at roughly the same times of day (near dawn & dusk) and also in roughly the same parts of the sky (relatively close to the horizon).

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Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by Chris Peterson » Sun Apr 04, 2010 11:38 pm

astrogimp wrote:If you are in the mountains the "Belt of Venus" is more commonly referred to as "alpenglow" and can turn both the low lying atmosphere and snow covered mountains opposite the sun pink; sometimes bright pink.
I live in the mountains, and we never refer to this as alpenglow. That term is reserved for the reflection of this light off of mountains. The color in the sky is not what we call the alpenglow. (Not saying you are wrong, just pointing out that there are likely to be regional differences in usage, and the two phenomena aren't necessarily seen as identical to everyone.)
Chris

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Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by Chris Peterson » Sun Apr 04, 2010 11:41 pm

astrix wrote:why does no one seem to call a spade a spade?
So you would have everybody refer to it as you do, a verbose description of the mechanism? That's why we use names- be it Belt of Venus or nightrise- to simplify our ability to discuss things.

BTW, the red is not related to refraction. It is the product of scatter.
Chris

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Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by astrogimp » Mon Apr 05, 2010 6:35 pm

According to Wikipedia,
"Alpenglow (from German: Alpenglühen) is an optical phenomenon. When the Sun is just below the horizon, a horizontal red glowing band can sometimes be observed on the opposite horizon. Alpenglow is easiest to observe when mountains are illuminated but can also be observed when the sky is illuminated through backscattering."
So, I would call both a pinkish looking snow covered mountain and the pinkish sky above it alpenglow but I would accept that there would be regional differences. If someone had called it the belt of Venus before I read this post I would not have known what they were talking about. You certainly learn new things by looking at the Astronomy Picture of the Day which of course is why I do it.

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Re: APOD: The Belt of Venus over the Valley of... (2010 Apr

Post by Star*Hopper » Tue Apr 06, 2010 7:29 am

Your point of regional and dialectic differences is well taken. Our people, when the phenomenum manifests itself, tend to vertically hop from one foot to the other, jabbing towards it with our index appendage while crying (in a rather gutteral vocé) "Ooo ooo looky looky" and glancing around excitedly to see whether other members of the tribe have also noticed it.

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