Starship Asterisk*

[quote=Dogger post_id=307113 time=1602451394]
Just wondering...if we see the Milky Way in this form (as an arc across the sky), where do we physically sit within it?

I had thought we were on the outer edge of one of the spiral arms, but wonder how that jibes with the photo (?)

Thanks
[/quote]

While we can, with some degree of accuracy, place ourselves in a map of our galaxy, it is easiest just to recognize that the galaxy is a flat disc with a bulge in the middle, and we're well out in that disk. Because we're in the plane of a disc of stars, we see our own galaxy as a line. That is, we only see, densely, the other stars that are also in the plane of that disc. If we look in any other direction, we only see the much, much smaller number of stars that are above or below us in that plane. And if we look toward the center of the galaxy, we see some of the bulge poking up and down out of the disc plane, which is apparent in the structure of the Milky Way in the region of Sagittarius.

Broadly, it wouldn't really matter where we were located in the disc of our galaxy. The Milky Way would look substantially similar.

Nice

[float=left][img3=Full 360º panorama map of the Milky Way with galactic north up]http://www.atlasoftheuniverse.com/galchart.gif[/img3][img3=Full 360º panorama view of the Milky Way (a mosaic of photographs by ESO), the galactic central bar is in the middle of the view, with galactic north up]https://upload.wikimedia.org/wikipedia/commons/thumb/6/60/ESO_-_Milky_Way.jpg/1920px-ESO_-_Milky_Way.jpg[/img3][img3=Observed (normal lines) and extrapolated (dotted lines) structure of the spiral arms of the Milky Way, viewed from "north" of the galaxy – stars generally move clockwise in this view. The gray lines radiating from the Sun's position (upper center) list the three-letter abbreviations of the corresponding constellations]https://upload.wikimedia.org/wikipedia/commons/thumb/1/1d/Milky_Way_Arms.svg/1024px-Milky_Way_Arms.svg.png[/img3][/float][quote=Dogger post_id=307113 time=1602451394]

Just wondering...if we see the Milky Way in this form (as an arc across the sky), where do we physically sit within it?

I had thought we were on the outer edge of one of the spiral arms, but wonder how that jibes with the photo (?)[/quote]
The APOD shows half (180º) of the Milky Way centered on the central bar [b][u][color=#0000FF]with galactic south up[/color][/u][/b].

:arrow: In [u]a full 360º (right side up)[/u] panorama map of the Milky Way [b][u][color=#FF0000]with galactic north up[/color][/u][/b] (shown at the left) the bright region to the left is looking towards [b][url=https://upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Cygnus_constellation_map.png/375px-Cygnus_constellation_map.png]Cygnus/the Northern Cross[/url] [u]down the [color=#EFAF00]Orion-Cygnus arm[/color][/u][/b].

:arrow: The bright region to the right ([u]above the LMC[/u]) is looking towards [b][url=https://upload.wikimedia.org/wikipedia/commons/c/cc/Deep_Crux_wide_field_with_fog.jpg]Crux/the Southern Cross[/url] [u]down the [color=#00BF00]Crux-Scutum arm[/color][/u][/b].

Both bright regions are visible in the 180º (upside down) APOD.

Just wondering...if we see the Milky Way in this form (as an arc across the sky), where do we physically sit within it?

I had thought we were on the outer edge of one of the spiral arms, but wonder how that jibes with the photo (?)

Thanks

[quote="E Fish" post_id=307097 time=1602425418 user_id=143902]
[quote=De58te post_id=307092 time=1602414915 user_id=141631]

And about monuments attention to detail. Do you know that the Great Pyramid of Giza was perfectly aligned to north and east. It was only off by a hundredth of a degree or so. That takes more planning than just two sticks. There is a Mayan pyramid that has exactly 365 steps to the top, and it also has a shadow of a snake on the staircase that can only be seen on the Solstice. That requires much more astronomical observations.[/quote]

Even if all it genuinely takes is two sticks, they have to [i]know[/i] that there's something to be marked with those two sticks. That means enough astronomical observation to be aware of the existence of solstices and equinoxes. That's not necessarily obvious if you're not paying detailed attention. I would be willing to bet that if you asked a number of people now what the solstice and the equinox actually mean, many wouldn't know why the day is longer or shorter.[/quote]
I would be willing to bet that if you asked [b][u][color=#00BF00]anyone in charge of ancient agrarian society[/color][/u][/b] what the solstices (and often even the equinoxes) actually meant they would know. Every boy scout knows that the shadow of the top of [url=https://www.haydenplanetarium.org/tyson/essays/2003-03-stick-in-the-mud-astronomy.php]a stick stuck in the ground[/url] moves from west to east (especially near solstice).

[attachment=0]PinnaclesGalaxy_Goh_1080.jpg[/attachment]

this fts my screen! :lol2:

[quote=De58te post_id=307092 time=1602414915 user_id=141631]
Do you know that the Great Pyramid of Giza was perfectly aligned to north and east. It was only off by a hundredth of a degree or so. That takes more planning than just two sticks.[/quote]

The positioning of the Great Pyramid is accurate to about a tenth of a degree. It is not sufficiently preserved to determine more than that, as the smooth facing is long since lost. And it is very much possible to achieve that degree of precision with nothing but sticks and string. I did an experiment which demonstrated just that, and presented it at an archaeoastronomy section at an Egyptology conference some years back.

[quote=De58te post_id=307092 time=1602414915 user_id=141631]
And about monuments attention to detail. Do you know that the Great Pyramid of Giza was perfectly aligned to north and east. It was only off by a hundredth of a degree or so. That takes more planning than just two sticks. There is a Mayan pyramid that has exactly 365 steps to the top, and it also has a shadow of a snake on the staircase that can only be seen on the Solstice. That requires much more astronomical observations.
[/quote]

Even if all it genuinely takes is two sticks, they have to [i]know[/i] that there's something to be marked with those two sticks. That means enough astronomical observation to be aware of the existence of solstices and equinoxes. That's not necessarily obvious if you're not paying detailed attention. I would be willing to bet that if you asked a number of people now what the solstice and the equinox actually mean, many wouldn't know why the day is longer or shorter. I required my students to mark the position of the Sun at sunrise over the course of two months so that they could see the shift of location. Heck, I have students who are just finding out that the Moon shines with reflected light from the Sun and couldn't figure out how the Moon could be illuminated by the Sun when it was on the other side of the Earth, and these are college students. Even the Greeks in Antiquity with their geocentric universe understood how the Moon shone.

So I completely agree. This is not just about "two sticks and getting up early". It's about having enough astronomical knowledge to be aware of the need to get up early with your two sticks.

...oh, and besides that, the picture is beautiful, even if composed. :mrgreen:

[quote=Ann post_id=307090 time=1602406566 user_id=129702]
I think it's sad to see the angry criticism against this APOD.

It is a beautiful, striking and stunning image.

Ann
[/quote]


[attachment=0]PinnaclesGalaxy_Goh_1080.jpg[/attachment]


I like it too Ann! It's a fantastic view!🤩 🌟 ✨
It'le iive in my wallpaper files :wink:

Re astro pixs going for the dramatic instead of reality. Astronomers have always loved the artistic pictures. How many times have we seen a Hubble photo with the statement "false colors"? The pictures as seen by the human eye would not sell astronomy magazines. Even NASA gets in on manipulation. Remember the Curiosity self portrait? The camera that took the picture is mysteriously floating in mid air. I don't think NASA had sent a flying camera with Curiosity. Something in photoshop was going on. And about monuments attention to detail. Do you know that the Great Pyramid of Giza was perfectly aligned to north and east. It was only off by a hundredth of a degree or so. That takes more planning than just two sticks. There is a Mayan pyramid that has exactly 365 steps to the top, and it also has a shadow of a snake on the staircase that can only be seen on the Solstice. That requires much more astronomical observations.

I think it is the Covid, Ann.

I think it's sad to see the angry criticism against this APOD.

It is a beautiful, striking and stunning image.

Ann

"detailed planning" I would have just moved the tripod to the appropriate place!
One of my triggers is when people claim detailed planning went into neolithic monuments so the sun would shine down corridors on the winter solstice when all it really took was two sticks and getting up early on a couple of days.

"Even so, the strong zodiacal light was a pleasant surprise. "
I have never seen the wedge-shaped zodiacal light with the moon present in the sky. Again, APOD is showing photoshopped, quasi-possible images for aesthetic, not astronomic.

[url=https://apod.nasa.gov/apod/ap201011.html] [img]https://apod.nasa.gov/apod/calendar/S_201011.jpg[/img] [size=150]Milky Way over the Pinnacles in Australia[/size][/url]

[b] Explanation: [/b] What strange world is this? [url=https://apod.nasa.gov/apod/ap150223.html]E[/url][url=https://apod.nasa.gov/apod/ap121017.html]a[/url][url=https://apod.nasa.gov/apod/ap150126.html]r[/url][url=https://apod.nasa.gov/apod/ap150412.html]t[/url][url=https://apod.nasa.gov/apod/ap130505.html]h[/url]. In the foreground of the featured image are the [url=https://en.wikipedia.org/wiki/The_Pinnacles_(Western_Australia)]Pinnacles[/url], unusual rock spires in [url=https://youtu.be/7XOkWFIjz_M]Nambung National Park[/url] in Western [url=https://en.wikipedia.org/wiki/Australia]Australia[/url]. Made of ancient sea shells ([url=https://www.chicagotribune.com/news/ct-xpm-2011-05-11-ct-x-c-fossils-in-chicagoland-buildin20110511-story.html]limestone[/url]), how these human-sized [url=https://www.youtube.com/watch?v=do7zg4wJfyE]picturesque spires[/url] formed remains unknown. In the background, just past the end of the central Pinnacle, is a bright crescent Moon. The eerie glow around the Moon is mostly [url=https://apod.nasa.gov/apod/ap140911.html]zodiacal light[/url], sunlight reflected by dust grains orbiting between the planets in the [url=https://solarsystem.nasa.gov/solar-system/our-solar-system/in-depth/]Solar System[/url]. Arching across the top is the central band of our [url=http://www.atlasoftheuniverse.com/galaxy.html]Milky Way Galaxy[/url]. Many famous [url=http://science.nasa.gov/astrophysics/focus-areas/how-do-stars-form-and-evolve/]stars[/url] and [url=https://apod.nasa.gov/apod/ap120106.html]nebulas[/url] are also visible in the background night sky. The featured 29-panel panorama was taken and composed in 2015 September after detailed planning that involved the Moon, the rock spires, and their corresponding [url=https://apod.nasa.gov/apod/ap150329.html]shadow[/url]s. Even so, the strong zodiacal light was a pleasant [url=https://www.featurepics.com/FI/Thumb300/20081130/Surprised-Kitten-986057.jpg]surprise[/url].


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