APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

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APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

Post by APOD Robot » Mon Mar 09, 2020 4:05 am

Image Milky Way and Zodiacal Light over Chile

Explanation: What is the band of light connecting the ground to the Milky Way? Zodiacal light -- a stream of dust that orbits the Sun in the inner Solar System. It is most easily seen just before sunrise, where it has been called a false dawn, or just after sunset. The origin of zodiacal dust remains a topic of research, but is hypothesized to result from asteroid collisions and comet tails. The featured wide-angle image shows the central band of our Milky Way Galaxy arching across the top, while the Large Magellanic Cloud (LMC), a satellite galaxy to our Milky Way, is visible on the far left. The image is a combination of over 30 exposures taken last July near La Serena among the mountains of Chile. During the next two months, zodiacal light can appear quite prominent in northern skies just after sunset.

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Ann
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Re: APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

Post by Ann » Mon Mar 09, 2020 5:50 am

Some kind of photographic technique has been used to make all straight lines look curved in this picture. The light pole looks rather drunk, for example. I don't mean it as a criticism.

Anyway, some of the effects on the sky (of this technique?) are interesting. My favorite effect is the apparent stellar stream connecting the Large Magellanic Cloud to the "end" of the Milky Way, as if the Milky Way in Vela was firing a pop corn machine gun of stars into the sky until all the pop corns popped all together to create the light show that is the LMC.

There is a milder but still interesting effect emerging from the other end of the Milky Way. There is what looks like a dividing line in the sky, on whose left side the night sky is bluish and on whose right side it is sort of brown.

And the Zodiacal light? Oh, I like it! :D

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Re: APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

Post by TheZuke! » Mon Mar 09, 2020 1:38 pm

Ann wrote:
Mon Mar 09, 2020 5:50 am
[...] as if the Milky Way in Vela was firing a pop corn machine gun of stars into the sky until all the pop corns popped all together to create the light show that is the LMC.

Ann
That's a "colourful" way of commenting!
B^)

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Re: APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

Post by Chris Peterson » Mon Mar 09, 2020 2:52 pm

Ann wrote:
Mon Mar 09, 2020 5:50 am
Some kind of photographic technique has been used to make all straight lines look curved in this picture. The light pole looks rather drunk, for example.
No technique has been used. It's just the consequence of mapping a sphere onto a plane. Something always has to give. (That's why countries lying far to the north or south tend to look way too big on most maps.) You can't make a wide angle image where all the straight lines in the 3D world appear so in a 2D projection (projections which try to achieve this create even more bizarre distortions). We almost always see this in Milky Way images, of course- a straight structure that appears as an arc in images.
Chris

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Re: APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

Post by Ann » Mon Mar 09, 2020 2:55 pm

Thanks for your explanation, Chris.

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Re: APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

Post by orin stepanek » Mon Mar 09, 2020 3:13 pm

Ann wrote:
Mon Mar 09, 2020 2:55 pm
Thanks for your explanation, Chris.

Ann
Ditto! At first i thought ot was a fisheye camera until I read the (over 30 exposures) explanation in the writeup!
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Re: APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

Post by Chris Peterson » Mon Mar 09, 2020 3:35 pm

orin stepanek wrote:
Mon Mar 09, 2020 3:13 pm
Ann wrote:
Mon Mar 09, 2020 2:55 pm
Thanks for your explanation, Chris.

Ann
Ditto! At first i thought ot was a fisheye camera until I read the (over 30 exposures) explanation in the writeup!
When you stitch together a bunch of images into a panorama, the stitching software typically offers multiple choices for the mapping used. "Fisheye" is one of those choices, where the resultant image will have the same kind of distortion that most fisheye lenses produce (cleverly known as "fisheye distortion"). There are other choices, as well, most long known to map makers.
Chris

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Re: APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

Post by orin stepanek » Mon Mar 09, 2020 3:48 pm

Chris Peterson wrote:
Mon Mar 09, 2020 3:35 pm
orin stepanek wrote:
Mon Mar 09, 2020 3:13 pm
Ann wrote:
Mon Mar 09, 2020 2:55 pm
Thanks for your explanation, Chris.

Ann
Ditto! At first i thought ot was a fisheye camera until I read the (over 30 exposures) explanation in the writeup!
When you stitch together a bunch of images into a panorama, the stitching software typically offers multiple choices for the mapping used. "Fisheye" is one of those choices, where the resultant image will have the same kind of distortion that most fisheye lenses produce (cleverly known as "fisheye distortion"). There are other choices, as well, most long known to map makers.
Thanks again Chris! 8-)
Orin

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Re: APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

Post by Confused Perspective » Tue Mar 10, 2020 5:08 pm

I never have understood the perspective of these types of shots. If we are within one of the spiral arms of the galaxy, how can this perspective of an arm be achieved from earth? Either we'd be looking out from within the same arm in the image and it doesn't make sense to me that it would look so sharp and defined, or we are looking at another arm and I would think it too far away to image from an earth based device plus the angle of the arm wouldn't make sense because we should see it edge-on being spiral galaxies more or less occupy a flat plane?

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Re: APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

Post by geckzilla » Tue Mar 10, 2020 6:14 pm

Confused Perspective wrote:
Tue Mar 10, 2020 5:08 pm
I never have understood the perspective of these types of shots. If we are within one of the spiral arms of the galaxy, how can this perspective of an arm be achieved from earth? Either we'd be looking out from within the same arm in the image and it doesn't make sense to me that it would look so sharp and defined, or we are looking at another arm and I would think it too far away to image from an earth based device plus the angle of the arm wouldn't make sense because we should see it edge-on being spiral galaxies more or less occupy a flat plane?
It's impossible to differentiate one arm of the Milky Way from another from looking at am image like this. We are viewing the disk of the MW, have a bit less than a 180° view, and can see the central bulge. Dust that seems to extend far above or below the plane is mostly a trick of perspective because it is relatively close to us.
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Re: APOD: Milky Way and Zodiacal Light over Chile (2020 Mar 09)

Post by Confused Perspective » Fri Mar 13, 2020 5:46 pm

Thanks geckzilla