APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

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APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by APOD Robot » Tue Jan 19, 2021 5:11 am

Image A Lunar Corona with Jupiter and Saturn

Explanation: Why does a cloudy moon sometimes appear colorful? The effect, called a lunar corona, is created by the quantum mechanical diffraction of light around individual, similarly-sized water droplets in an intervening but mostly-transparent cloud. Since light of different colors has different wavelengths, each color diffracts differently. Lunar Coronae are one of the few quantum mechanical color effects that can be easily seen with the unaided eye. Solar coronae are also sometimes evident. The featured composite image was captured a few days before the close Great Conjunction between Saturn and Jupiter last month. In the foreground, the Italian village of Pieve di Cadore is visible in front of the Sfornioi Mountains.

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Re: APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by orin stepanek » Tue Jan 19, 2021 12:21 pm

CoronaConjunction_Masi_1080_annotated.jpg

This is both a beautiful landscape, and skyscape! :D
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Re: APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by Sa Ji Tario » Tue Jan 19, 2021 2:11 pm

More than one of Jupiter's moons can be seen

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Titian da Cadore & Adonis's hat

Post by neufer » Tue Jan 19, 2021 2:47 pm

https://en.wikipedia.org/wiki/Titian wrote:
<<Tiziano Vecelli or Vecellio (c. 1489 – 27 August 1576), known in English as Titian, was an Italian painter during the Renaissance, considered the most important member of the 16th-century Venetian school. Titian was born in Pieve di Cadore, near Belluno, (then in the Republic of Venice). During his lifetime he was often called da Cadore, 'from Cadore', taken from his native region. Recognized by his contemporaries as "The Sun Amidst Small Stars" (recalling the final line of Dante's Paradiso), Titian was one of the most versatile of Italian painters, equally adept with portraits, landscape backgrounds, and mythological and religious subjects. His painting methods, particularly in the application and use of colour, exercised a profound influence not only on painters of the late Italian Renaissance, but on future generations of Western art.>>
https://hankwhittemore.com/2011/05/14/1230/ wrote: Hank Whittemore's Shakespeare Blog
Titian’s Painting of “Venus and Adonis”


And with his bonnet hides his angry brow…

<<The author of Venus and Adonis by “William Shakespeare” (1593) describes a painting by Tiziano Vecellio, or Titian, in which Adonis wears a bonnet or cap. This was the only Titian painting with that detail and, during Shakespeare’s time, it could have been seen only at Titian’s home in Venice. William of Stratford had never left England, but Edward de Vere the 17th Earl of Oxford had traveled throughout Italy during 1575-1576 (at age twenty-five), making his home base in Venice, where Titian worked until his death on August 27, 1576.

I continue to be struck by the simplicity and clarity of this piece of factual evidence presented in an article by the brilliant scholar Dr. Noemi Magri in Great Oxford: Essays on the Life and Works of Edward de Vere (2004), a collection of papers from the De Vere Society in England. In her essay, entitled The Influence of Italian Renaissance Art on Shakespeare’s Works; Titian’s Barberini Painting: the Pictorial Source of “Venus and Adonis,” Dr. Magri writes that Titian made many replicas of his work and that Shakespeare based his poem on the ONLY autographed replica in which Adonis wears a bonnet or hat:

Titian’s painting was his source of inspiration, the thing that stimulated him to write a poem about this subject though he also had a thorough knowledge of Ovid … Shakespeare describes the painting in detail: he portrays the painting in words and the description is too faithful to ascribe it to mere coincidence… It is evident that Shakespeare’s Adonis is wearing a hat, a bonnet. The mention of the bonnet is not coincidental. This is the detail here taken as evidence of the pictorial source.>>
Art Neuendorffer

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Re: APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by johnnydeep » Tue Jan 19, 2021 3:52 pm

Sa Ji Tario wrote:
Tue Jan 19, 2021 2:11 pm
More than one of Jupiter's moons can be seen
You're right! Thanks for making me look.
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Re: APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by johnnydeep » Tue Jan 19, 2021 4:12 pm

APOD Robot wrote:
Tue Jan 19, 2021 5:11 am
Image A Lunar Corona with Jupiter and Saturn

Explanation: Why does a cloudy moon sometimes appear colorful? The effect, called a lunar corona, is created by the quantum mechanical diffraction of light around individual, similarly-sized water droplets in an intervening but mostly-transparent cloud. Since light of different colors has different wavelengths, each color diffracts differently. Lunar Coronae are one of the few quantum mechanical color effects that can be easily seen with the unaided eye. Solar coronae are also sometimes evident. The featured composite image was captured a few days before the close Great Conjunction between Saturn and Jupiter last month. In the foreground, the Italian village of Pieve di Cadore is visible in front of the Sfornioi Mountains.
My, what a lovely bunch of hyperlinks this has! I think a future APOD should attempt to have a meaningful link on every single word in the description! 8-)

Now, about this "diffraction" concept. I'm confused, and the WikiPedia link - https://en.wikipedia.org/wiki/Diffraction - only made it worse. Is there a fundamental difference between diffraction and refraction or are they both a result of the same underlying quantum mechanical effect? So far I have:

Diffraction - bending of waves when travelling through or around an object (slit, water droplet, etc)
Refraction - bending of waves when travelling through mediums of differing densities or thicknesses (air versus water, prisms, lenses, etc)
Reflection - bouncing of waves off matter (mirrors, water, skin, etc)

And what about rainbows? Water droplets in the sky with sunlight passing through and around them. So is a rainbow the result of refraction or diffraction... or both?

As for quantum mechanical effects, I suppose when it all comes down to it, ultimately EVERYTHING is caused by them!
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Re: APOD: The Medulla Nebula Supernova Remnant (2021 Jan 18)

Post by Fred the Cat » Tue Jan 19, 2021 5:56 pm

A few years ago I was out with friends early one morning and noticed the moon being obscured by fog.
IMG_5004.JPG
As the mist deepened the effect became more enhanced
IMG_5015.JPG
until the scene became quite beautiful. :ssmile:
IMG_5028 (2).JPG
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Re: APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by Chris Peterson » Tue Jan 19, 2021 6:03 pm

johnnydeep wrote:
Tue Jan 19, 2021 4:12 pm
Now, about this "diffraction" concept. I'm confused, and the WikiPedia link - https://en.wikipedia.org/wiki/Diffraction - only made it worse. Is there a fundamental difference between diffraction and refraction or are they both a result of the same underlying quantum mechanical effect? So far I have:

Diffraction - bending of waves when travelling through or around an object (slit, water droplet, etc)
Refraction - bending of waves when travelling through mediums of differing densities or thicknesses (air versus water, prisms, lenses, etc)
Reflection - bouncing of waves off matter (mirrors, water, skin, etc)

And what about rainbows? Water droplets in the sky with sunlight passing through and around them. So is a rainbow the result of refraction or diffraction... or both?
Note that refraction involves a medium. Diffraction does not.

Light travels at less than c in any medium, and different wavelengths travel at different speeds in mediums. So an element of refraction (which is a consequence of light traveling at different speeds across material boundaries) is the fact that different wavelengths (colors) are bent different amounts, resulting in the separation of colors. This property is called dispersion, and it's how prisms... and rainbows... work.

As a rule, we usually explain the behavior of light when it interacts with bodies larger than the wavelength of light using classical (non-quantum) approaches. When the interaction occurs with bodies smaller than the wavelength of light, quantum explanations are usually better. Raindrops are big compared with the wavelength of visible light. But tiny drops of water or ice in the atmosphere can be much smaller, so diffraction becomes the dominant influence, not refraction.
Chris

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Re: APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by FrostyBoy » Tue Jan 19, 2021 8:03 pm

First time contributor. If solar coronae are sun dogs, wouldn't lunar coronae be: moondoggies? Saw plenty of sun dogs working at McMurdo Station, have never seen a lunar coronae. Thanks for all the work APOD does to raise the astronomy IQ of the world. David

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Re: APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by Chris Peterson » Tue Jan 19, 2021 8:46 pm

FrostyBoy wrote:
Tue Jan 19, 2021 8:03 pm
First time contributor. If solar coronae are sun dogs, wouldn't lunar coronae be: moondoggies? Saw plenty of sun dogs working at McMurdo Station, have never seen a lunar coronae. Thanks for all the work APOD does to raise the astronomy IQ of the world. David
Sundogs and moondogs are unrelated to coronas. They are found around the common 22° halo, and are caused by refraction and internal reflection in ice crystals. Coronas are quite common, as well, although it's a lot easier to see lunar ones than solar... the latter usually only visible when you block the intense glare from the Sun with a thumb or light post.
Chris

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Re: APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by orin stepanek » Tue Jan 19, 2021 9:16 pm

Might be changing the subject some, but the weather Channel showed a beautiful son pillar the other day! It seemed to go up forever! Of course thr=ey use a lot of photo technology; so it might have been faked! :shock:
Orin

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Re: APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by johnnydeep » Tue Jan 19, 2021 10:18 pm

Chris Peterson wrote:
Tue Jan 19, 2021 6:03 pm
johnnydeep wrote:
Tue Jan 19, 2021 4:12 pm
Now, about this "diffraction" concept. I'm confused, and the WikiPedia link - https://en.wikipedia.org/wiki/Diffraction - only made it worse. Is there a fundamental difference between diffraction and refraction or are they both a result of the same underlying quantum mechanical effect? So far I have:

Diffraction - bending of waves when travelling through or around an object (slit, water droplet, etc)
Refraction - bending of waves when travelling through mediums of differing densities or thicknesses (air versus water, prisms, lenses, etc)
Reflection - bouncing of waves off matter (mirrors, water, skin, etc)

And what about rainbows? Water droplets in the sky with sunlight passing through and around them. So is a rainbow the result of refraction or diffraction... or both?
Note that refraction involves a medium. Diffraction does not.

Light travels at less than c in any medium, and different wavelengths travel at different speeds in mediums. So an element of refraction (which is a consequence of light traveling at different speeds across material boundaries) is the fact that different wavelengths (colors) are bent different amounts, resulting in the separation of colors. This property is called dispersion, and it's how prisms... and rainbows... work.

As a rule, we usually explain the behavior of light when it interacts with bodies larger than the wavelength of light using classical (non-quantum) approaches. When the interaction occurs with bodies smaller than the wavelength of light, quantum explanations are usually better. Raindrops are big compared with the wavelength of visible light. But tiny drops of water or ice in the atmosphere can be much smaller, so diffraction becomes the dominant influence, not refraction.
Thanks, that helps some.
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Re: APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by saturno2 » Tue Jan 19, 2021 10:19 pm

Interesting image

FrostyBoy

Re: APOD: A Lunar Corona with Jupiter and Saturn (2021 Jan 19)

Post by FrostyBoy » Wed Jan 20, 2021 7:56 am

Chris, thanks for the explanation on lunar and solar coronae, will dig in a bit on your input. Just found my 90 mm reflector telescope buried in the attic the last 10 years...hoping to conduct some stargazing events for the neighbors. Cheers! David