APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

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APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by APOD Robot » Mon Jul 22, 2019 4:10 am

Image HDR: Earth's Circular Shadow on the Moon

Explanation: What could create such a large circular shadow on the Moon? The Earth. Last week's full Moon -- the Buck Moon -- was so full that it fell almost exactly in a line with the Sun and the Earth. When that happens the Earth casts its shadow onto the Moon. The circularity of the Earth's shadow on the Moon was commented on by Aristotle and so has been noticed since at least the 4th century BC. What's new is humanity's ability to record this shadow with such high dynamic range (HDR). The featured HDR composite of last week's partial lunar eclipse combines 15 images and include an exposure as short as 1/400th of a second -- so as not to overexpose the brightest part -- and an exposure that lasted five seconds -- to bring up the dimmest part. This dimmest part -- inside Earth's umbra -- is not completely dark because some light is refracted through the Earth's atmosphere onto the Moon. A total lunar eclipse will occur next in 2021 May.

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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by JohnD » Mon Jul 22, 2019 8:40 am

On an astronomy website, why are subjective and imaginary ideas like the "Buck Moon" introduced? Any full moon varies in date by more than a fortnight, and has absolutely no prognostic significance. It's complete nonsense. Please APOD, confine your remarks to the astronomical significance of your images, and leave astrology to the whoo-whoos.
And, that's a smashing picture! Love it!
John

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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by heehaw » Mon Jul 22, 2019 8:41 am

Oooohhhhh! Lovely! The best lunar eclipse photo ever! The crispness of the edge of Earth's circular shadow on the Moon!

heehaw

Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by heehaw » Mon Jul 22, 2019 8:44 am

(And I strongly agree with JohnD on avoiding 'Supermoon' and other name crap!)

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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by Boomer12k » Mon Jul 22, 2019 10:00 am

Awesome image.... since 4th century BC?????....they KNEW the Earth cast a shadow on the Moon, and it was CURVED???? That must have been common knowledge then...why was there ever a "Flat Earth"? Could that have just been a JOKE for the masses or something? "Shecky Aurelius"...at the Forum??? "Yeah, how 'bout that Flat Earth folks? I'm afraid of ocean voyages because I might fall off." Ba-dumpt!!! Yeah, hysterical stuff...
I mean... really....how could that have lasted so long? Well...there IS Ptolemy....

I don't mind the not-so-scientific labels for things...after all...are we then going to drop all labels because they are based on another culture, or Mythology? "Jupiter" is now called WHAT???? and are just as much "Astrology"? Have some tolerance...

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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by JohnD » Mon Jul 22, 2019 11:39 am

Why was there a "Flat Earth"? Because of DiscWorld, or course! And you can't fall off because of the Rim Fence!
And by the way, it's turtles, all the way down!

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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by orin stepanek » Mon Jul 22, 2019 11:59 am

Today's APOD= +1 :clap: :thumb_up: :yes: OOO; they only allow 3 emoji!
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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by neufer » Mon Jul 22, 2019 12:22 pm


Boomer12k wrote:
Mon Jul 22, 2019 10:00 am

Awesome image.... since 4th century BC?????....they KNEW the Earth cast a shadow on the Moon, and it was CURVED???? That must have been common knowledge then...why was there ever a "Flat Earth"?
Judging from this shadow: https://apod.nasa.gov/apod/ap190609.html

:arrow: My best guess is that the Earth is a pentagon.
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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by E Fish » Mon Jul 22, 2019 1:21 pm

Boomer12k wrote:
Mon Jul 22, 2019 10:00 am
Awesome image.... since 4th century BC?????....they KNEW the Earth cast a shadow on the Moon, and it was CURVED???? That must have been common knowledge then...why was there ever a "Flat Earth"? Could that have just been a JOKE for the masses or something? "Shecky Aurelius"...at the Forum??? "Yeah, how 'bout that Flat Earth folks? I'm afraid of ocean voyages because I might fall off." Ba-dumpt!!! Yeah, hysterical stuff...
I mean... really....how could that have lasted so long? Well...there IS Ptolemy....

I don't mind the not-so-scientific labels for things...after all...are we then going to drop all labels because they are based on another culture, or Mythology? "Jupiter" is now called WHAT???? and are just as much "Astrology"? Have some tolerance...

:---[===] *
From what I've researched about this (it's a pet peeve of mine), there was one scholar in the fifth-century, in the Byzantine empire, who proposed the possibility that the Earth was actually flat, not spherical. One. Now, what the common people thought is unknown because there was so much illiteracy in the ancient and medieval worlds, but even the Christian church (long before Catholicism) subscribed to a spherical Earth, as did the medieval Muslims. What happened was that some pedagogy instructor found that source back in the 19th century and assumed that one source stating it as a possibility meant that everyone thought the world was flat. He could also use 5000 year old images from ancient Egypt of the goddess Nut stretching over the world as evidence.

Beyond that guy, there are no scholarly texts from the ancient world advocating for a flat earth. Ptolemy knew it was spherical. Aristotle knew it was spherical. The scholars in the House of Wisdom in Baghdad knew it was spherical. Christopher Columbus was not proving the Earth was spherical. He was proving that he could get to the East Indies faster by sailing west than by following the Portuguese sailors around the horn of Africa. And it's a good thing there were two big continents in the way because his estimates for the size of the Earth were waaaaay off and he would certainly have died with no port of call for 15,000 miles. I tell my students that there are more people today who believe the Earth is flat than ever did in Antiquity.

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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by Chris Peterson » Mon Jul 22, 2019 1:27 pm

JohnD wrote:
Mon Jul 22, 2019 8:40 am
On an astronomy website, why are subjective and imaginary ideas like the "Buck Moon" introduced? Any full moon varies in date by more than a fortnight, and has absolutely no prognostic significance. It's complete nonsense. Please APOD, confine your remarks to the astronomical significance of your images, and leave astrology to the whoo-whoos.
And, that's a smashing picture! Love it!
John
Because astronomy is about much more than just the science behind the Universe. It's also embedded in our history and culture. So please, APOD, keep making references to fun bits of cultural trivia that overlap with astronomy.
Chris

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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by neufer » Mon Jul 22, 2019 1:54 pm

E Fish wrote:
Mon Jul 22, 2019 1:21 pm

From what I've researched about this (it's a pet peeve of mine), there was one scholar in the fifth-century, in the Byzantine empire, who proposed the possibility that the Earth was actually flat, not spherical. One. Now, what the common people thought is unknown because there was so much illiteracy in the ancient and medieval worlds, but even the Christian church (long before Catholicism) subscribed to a spherical Earth, as did the medieval Muslims. What happened was that some pedagogy instructor found that source back in the 19th century and assumed that one source stating it as a possibility meant that everyone thought the world was flat. He could also use 5000 year old images from ancient Egypt of the goddess Nut stretching over the world as evidence. Beyond that guy, there are no scholarly texts from the ancient world advocating for a flat earth. Ptolemy knew it was spherical. Aristotle knew it was spherical. The scholars in the House of Wisdom in Baghdad knew it was spherical. Christopher Columbus was not proving the Earth was spherical. He was proving that he could get to the East Indies faster by sailing west than by following the Portuguese sailors around the horn of Africa. And it's a good thing there were two big continents in the way because his estimates for the size of the Earth were waaaaay off and he would certainly have died with no port of call for 15,000 miles. I tell my students that there are more people today who believe the Earth is flat than ever did in Antiquity.
https://en.wikipedia.org/wiki/Myth_of_the_flat_Earth#Irving's_biography_of_Columbus wrote:
Click to play embedded YouTube video.
<<In 1828, Washington Irving's highly romanticized biography, A History of the Life and Voyages of Christopher Columbus, was published and mistaken by many for a scholarly work. In Book II, Chapter IV of this biography, Irving gave a largely fictional account of the meetings of a commission established by the Spanish sovereigns to examine Columbus's proposals. One of his more fanciful embellishments was a highly unlikely tale that the more ignorant and bigoted members on the commission had raised scriptural objections to Columbus's assertions that the Earth was spherical.

The issue in the 1490s was not the shape of the Earth, but its size, and the position of the east coast of Asia, as Irving in fact points out. Historical estimates from Ptolemy onward placed the coast of Asia about 180° east of the Canary Islands. Columbus adopted an earlier (and rejected) distance of 225°, added 28° (based on Marco Polo's travels), and then placed Japan another 30° further east. Starting from Cape St. Vincent in Portugal, Columbus made Eurasia stretch 283° to the east, leaving the Atlantic as only 77° wide. Since he planned to leave from the Canaries (9° further west), his trip to Japan would only have to cover 68° of longitude.

Columbus mistakenly assumed that the mile referred to in the Arabic estimate of 56⅔ miles for the size of a degree was the same as the actually much shorter Italian mile of 1,480 meters. His estimate for the size of the degree and for the circumference of the Earth was therefore about 25% too small. The combined effect of these mistakes was that Columbus estimated the distance to Japan to be only about 5,000 km (or only to the eastern edge of the Caribbean) while the true figure is about 20,000 km. The Spanish scholars may not have known the exact distance to the east coast of Asia, but they believed that it was significantly further than Columbus's projection; and this was the basis of the criticism in Spain and Portugal, whether academic or among mariners, of the proposed voyage.

The disputed point was not the shape of the Earth, nor the idea that going west would eventually lead to Japan and China, but the ability of European ships to sail that far across open seas. The small ships of the day (Columbus's three ships varied between 20.5 and 23.5 m – or 67 to 77 feet – in length and carried about 90 men) simply could not carry enough food and water to reach Japan. The ships barely reached the eastern Caribbean islands. Already the crews were mutinous, not because of some fear of "sailing off the edge", but because they were running out of food and water with no chance of any new supplies within sailing distance. They were on the edge of starvation. What saved Columbus was the unknown existence of the Americas precisely at the point he thought he would reach Japan. His ability to resupply with food and water from the Caribbean islands allowed him to return safely to Europe. Otherwise his crews would have died, and the ships foundered.>>
Last edited by neufer on Mon Jul 22, 2019 2:13 pm, edited 1 time in total.
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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by Chris Peterson » Mon Jul 22, 2019 2:07 pm

E Fish wrote:
Mon Jul 22, 2019 1:21 pm
I tell my students that there are more people today who believe the Earth is flat than ever did in Antiquity.
Probably not the case (although it varies with culture and just what we want to call "antiquity"). For at least the last two or three thousand years, it's likely that most educated people understood the Earth to be spherical. But most people weren't educated. In western cultures, most people probably considered the Earth to be flat. (This is all complicated by the fact that some very different epistemological systems existed; even highly educated people found no contradiction in believing that the Earth was both spherical and flat at the same time.)
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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by neufer » Mon Jul 22, 2019 2:33 pm

Chris Peterson wrote:
Mon Jul 22, 2019 2:07 pm
E Fish wrote:
Mon Jul 22, 2019 1:21 pm

I tell my students that there are more people today who believe the Earth is flat than ever did in Antiquity.
Probably not the case (although it varies with culture and just what we want to call "antiquity"). For at least the last two or three thousand years, it's likely that most educated people understood the Earth to be spherical. But most people weren't educated. In western cultures, most people probably considered the Earth to be flat. (This is all complicated by the fact that some very different epistemological systems existed; even highly educated people found no contradiction in believing that the Earth was both spherical and flat at the same time.)
https://en.wikipedia.org/wiki/Earth_Song wrote:
Click to play embedded YouTube video.
<<"Earth Song" is a song by American singer Michael Jackson from his ninth studio album HIStory: Past, Present and Future, Book I. It was released on November 27, 1995 as the third single from the album. "Earth Song" is a ballad that incorporates elements of blues, gospel and opera. In the socially conscious track, Jackson issues a wakeup-call about the dire situations that mankind has caused and is facing, ranging from war to devastation to animals and earth itself. The song reveals itself to be highly spiritual at the end where Jackson calls on people to remember the earth is their inheritance from God via their ancestor Abraham. "What about death again" reminds all to think about eternal death, asking people to check their heart for repentance, or to see if they really cared at all.

"Earth Song" is written in the key of G♯ minor,
but later modulates to B FLAT minor.
>>
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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by JohnD » Mon Jul 22, 2019 5:17 pm

There is more beauty in heaven and earth, Christopher, than is dreamt of in your philosophy. But "Buck Moon"?
Allegedly so named by the Native American Peoples, so acknowledge that, but also that the Full Moon of July is also named Thunder Moon, Wort Moon, and Hay Moon from Old English/Anglo-Saxon, so recognsie that too, else APOD discriminates on ethnicity. And you wouldn't want that, would you? A name for the month's full moon is a complete invention, that every source I can find traces back to the Farmers Almanac (founded 1792).

But the beauty - one of the beauties - of science and it's daughter astronomy, is that with plenty of dispute and discussion, and imagination, any argument is based on facts. Facts and testable theories. So, lets test the theory that the July full moon is the Buck Moon. Let's ask someone living in the Southern Hemisphere. There it may be called the Wolf Moon, Old Moon or Ice Moon! Because there, it's Mid Winter!

And the photograph was taken by an Italian, Christian Fattinnnanzi, so what's the July Full Moon called in Italian? Ah! "Luglio luna piena"!
Which translates as "July Full Moon"

Buck Moon? BUSTED!
John

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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by geckzilla » Mon Jul 22, 2019 5:33 pm

JohnD wrote:
Mon Jul 22, 2019 5:17 pm
There is more beauty in heaven and earth, Christopher, than is dreamt of in your philosophy. But "Buck Moon"?
Allegedly so named by the Native American Peoples, so acknowledge that, but also that the Full Moon of July is also named Thunder Moon, Wort Moon, and Hay Moon from Old English/Anglo-Saxon, so recognsie that too, else APOD discriminates on ethnicity. And you wouldn't want that, would you? A name for the month's full moon is a complete invention, that every source I can find traces back to the Farmers Almanac (founded 1792).

But the beauty - one of the beauties - of science and it's daughter astronomy, is that with plenty of dispute and discussion, and imagination, any argument is based on facts. Facts and testable theories. So, lets test the theory that the July full moon is the Buck Moon. Let's ask someone living in the Southern Hemisphere. There it may be called the Wolf Moon, Old Moon or Ice Moon! Because there, it's Mid Winter!

And the photograph was taken by an Italian, Christian Fattinnnanzi, so what's the July Full Moon called in Italian? Ah! "Luglio luna piena"!
Which translates as "July Full Moon"

Buck Moon? BUSTED!
John
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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by Chris Peterson » Mon Jul 22, 2019 5:48 pm

JohnD wrote:
Mon Jul 22, 2019 5:17 pm
There is more beauty in heaven and earth, Christopher, than is dreamt of in your philosophy. But "Buck Moon"?
Allegedly so named by the Native American Peoples, so acknowledge that, but also that the Full Moon of July is also named Thunder Moon, Wort Moon, and Hay Moon from Old English/Anglo-Saxon, so recognsie that too, else APOD discriminates on ethnicity. And you wouldn't want that, would you? A name for the month's full moon is a complete invention, that every source I can find traces back to the Farmers Almanac (founded 1792).

But the beauty - one of the beauties - of science and it's daughter astronomy, is that with plenty of dispute and discussion, and imagination, any argument is based on facts. Facts and testable theories. So, lets test the theory that the July full moon is the Buck Moon. Let's ask someone living in the Southern Hemisphere. There it may be called the Wolf Moon, Old Moon or Ice Moon! Because there, it's Mid Winter!

And the photograph was taken by an Italian, Christian Fattinnnanzi, so what's the July Full Moon called in Italian? Ah! "Luglio luna piena"!
Which translates as "July Full Moon"

Buck Moon? BUSTED!
John
Why, thank you! This forum exists to answer questions and fill in details that there isn't room for in the short caption. Nice work.
Chris

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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by JohnD » Mon Jul 22, 2019 7:00 pm

Chris, your modest praise disarms me!

But I would not presume to provide added value as others do, on the scale of, say, neufer!
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Re: APOD: HDR: Earth's Circular Shadow on the Moon (2019 Jul 22)

Post by E Fish » Tue Jul 23, 2019 3:04 am

Chris Peterson wrote:
Mon Jul 22, 2019 2:07 pm
E Fish wrote:
Mon Jul 22, 2019 1:21 pm
I tell my students that there are more people today who believe the Earth is flat than ever did in Antiquity.
Probably not the case (although it varies with culture and just what we want to call "antiquity"). For at least the last two or three thousand years, it's likely that most educated people understood the Earth to be spherical. But most people weren't educated. In western cultures, most people probably considered the Earth to be flat. (This is all complicated by the fact that some very different epistemological systems existed; even highly educated people found no contradiction in believing that the Earth was both spherical and flat at the same time.)
Certainly, as I said, it's well nigh impossible to ascertain what the uneducated believed in that time, but I would venture to guess that many didn't waste time worrying about it. Sailors were generally aware of the curvature. But at least in the Middle Ages (app. 500-1450), if people were thinking about it, they generally would take their cue from the church and the church generally followed Aristotle. Not in everything by any means. That whole eternal universe gave them problems, but even in Dante's Divine Comedy, it is taken for granted that the Earth is a sphere.

One reason I do say it is just to get their attention. This is one of those topics that I just can't believe is still up for discussion in this day and age. I don't remember people talking about it at all when I was in college or in grad school. For me, at least, it seems like it just popped up out of nowhere.