APOD: Night Sky Reflected (2021 Sep 13)

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APOD: Night Sky Reflected (2021 Sep 13)

Post by APOD Robot » Mon Sep 13, 2021 4:05 am

Image Night Sky Reflected

Explanation: What's that in the mirror? In the featured image of the dark southern sky, the three brightest galaxies of the night are all relatively easy to identify. Starting from the left, these are the Small Magellanic Cloud (SMC), the Large Magellanic Cloud (LMC), and part of the central band of our Milky Way Galaxy. All three are also seen reflected in a shallow pool of water. But what is seen in the mirror being positioned by the playful astrophotographer? Dust clouds near the center of our Milky Way -- and the planet Jupiter. The composite was carefully planned and composed from images captured from the same camera in the same location and during the same night in mid-2019 in Mostardas, south Brazil. The picture won first place in the Connecting to the Dark division of the International Dark-Sky Association's Capture the Dark contest for 2021.

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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by Guest » Mon Sep 13, 2021 4:17 am

The Pipe Nebula.

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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by Ann » Mon Sep 13, 2021 5:53 am

Beautiful APOD with a lot to annotate! :D

Starry night reflected Egon Filter.png

1) NGC 3532. Image by ESO/G. Beccari.

2) The Carina Nebula. Image by Harel Boren. The brightest light in Boren's image , just above and slightly to the left of the large V-shaped dust lane, is Eta Carina. Ultraviolet image by ESA/Hubble.

3) IC 2602. Picture by Fred Espenak. Hope I get to keep it!

4) NGC 3114. Picture by Sergio Eguivar.

5) Just some random stars with Iota Carina and HD 79351 in the center.

6) NGC 2516. Image by Mike O'Day.

7) Canopus?

8) Large Magellanic Cloud. Robert Gendler/ESO.

9) The Tarantula Nebula. Image: TRAPPIST/E. Jehin/ESO.

10) Small Magellanic Cloud. Image: ESA/Hubble.

11) 47 Tucanae, 47 Tuc, second brightest globular cluster of the Milky Way. Image: ESA/Hubble.

12) 47 Tuc reflected.

13) Small Magellanic Cloud reflected.

14) Pipe Nebula. Brightest blue star above the Pipe Nebula is Theta Ophiuchi. Image: ESO/Yuri Beletsky.

15) Jupiter! Image: NASA, ESA, A. Simon (Goddard Space Flight Center), and M.H. Wong (University of California, Berkeley).

16) Large Magellanic Cloud reflected.

17) Tarantula nebula reflected.

18) NGC 2516 reflected.

19) Iota Carina and HD 79351 reflected.

Phew! Time for a break now.

Ann
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by rorunner@gmail.com » Mon Sep 13, 2021 6:37 am

Wonderful APOD! Congratulations!!!!!

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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by NCTom » Mon Sep 13, 2021 12:03 pm

Ann, you are a wonder! Thanks so much.

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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by mfstrollo » Mon Sep 13, 2021 12:32 pm

The double reflection is the face of the mirror holder.

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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by orin stepanek » Mon Sep 13, 2021 12:35 pm

GalaxySkyMirror_Egon_960.jpg
I like how the SMG & LMG show up in this beautiful Photo!
The lake being frozen hard helps tht photographer do his thing! :mrgreen:
giphy.gif
Be nice kitty! :lol2:
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by DeepintheHeartofTexas » Mon Sep 13, 2021 1:48 pm

Is anyone else bothered/confused by the mirror's impossible reflection in the lake?

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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by johnnydeep » Mon Sep 13, 2021 2:08 pm

DeepintheHeartofTexas wrote:
Mon Sep 13, 2021 1:48 pm
Is anyone else bothered/confused by the mirror's impossible reflection in the lake?
Yeah, now that you mention it :) Also, clearly, the guy can't be standing IN the lake, so now I don't understand what I'm looking at all! The links don't seem to provide any more info about how this image was created.

EDIT: oh wait - is the lake actually frozen? I see the guy is wearing a hat, and now also the snow in the background. D'oh! But I still don't understand the mirror's reflection in the ice (or water).

EDIT #2: on the other hand, this pic was taken from Mostardas, south Brazil. Does it ever get cold enough there for snow or frozen lakes?
Last edited by johnnydeep on Mon Sep 13, 2021 3:31 pm, edited 3 times in total.
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by Chris Peterson » Mon Sep 13, 2021 2:10 pm

orin stepanek wrote:
Mon Sep 13, 2021 12:35 pm
I like how the SMG & LMG show up in this beautiful Photo!
The lake being frozen hard helps tht photographer do his thing!
The lake isn't frozen. He's standing in shallow water.
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by Fred the Cat » Mon Sep 13, 2021 2:34 pm

Hope that isn't the primary for his square telescope. :wink: I guess those are actually round. :ssmile:
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by Ann » Mon Sep 13, 2021 3:13 pm

Chris Peterson wrote:
Mon Sep 13, 2021 2:10 pm
orin stepanek wrote:
Mon Sep 13, 2021 12:35 pm
I like how the SMG & LMG show up in this beautiful Photo!
The lake being frozen hard helps tht photographer do his thing!
The lake isn't frozen. He's standing in shallow water.
Yes, that's how I understood it. The night must have been extremely calm, with no wind.

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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by MarkBour » Mon Sep 13, 2021 3:26 pm

The star tracks in the lake are much longer than in the sky or upper mirror image. I assume a longer exposure was needed because the reflection from the lake surface is not so bright as the sky light. It's all very interesting.
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by orin stepanek » Mon Sep 13, 2021 3:38 pm

Chris Peterson wrote:
Mon Sep 13, 2021 2:10 pm
orin stepanek wrote:
Mon Sep 13, 2021 12:35 pm
I like how the SMG & LMG show up in this beautiful Photo!
The lake being frozen hard helps tht photographer do his thing!
The lake isn't frozen. He's standing in shallow water.
Yup; being in Brazil; you're right about it not being frozen; but look at the wheels on the cart! They are not in water! Me thinks a lot of photo tricks going on!
Oh wait; That's not a cart; but the shadow of his mirror1 How did he accomplish that!
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by neufer » Mon Sep 13, 2021 3:50 pm

MarkBour wrote:
Mon Sep 13, 2021 3:26 pm

The star tracks in the lake are much longer than in the sky or upper mirror image. I assume a longer exposure was needed because the reflection from the lake surface is not so bright as the sky light. It's all very interesting.
The star tracks in the lake are much longer than in the sky or upper mirror image because of motions on the lake surface. (A time exposure would spread the starlight left-to-right not up & down.) Chris has pointed out before that lake surfaces spread bright point-like starlight over multiple pixels such that saturated bright stars are actually more prominent in the reflection. Dim and/or extended objects do not share in this enhancement.
Last edited by neufer on Mon Sep 13, 2021 4:13 pm, edited 2 times in total.
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by neufer » Mon Sep 13, 2021 3:59 pm

Click to play embedded YouTube video.
orin stepanek wrote:
Mon Sep 13, 2021 3:38 pm


Oh wait; That's not a cart; but the shadow of his mirror1 How did he accomplish that!
That's a water reflection of his mirror containing his own face against an unrevealed piece of sky that RJN has put forth a Quiz challenge.

Anyone figured it out yet :?:
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by Chris Peterson » Mon Sep 13, 2021 4:14 pm

neufer wrote:
Mon Sep 13, 2021 3:59 pm
orin stepanek wrote:
Mon Sep 13, 2021 3:38 pm

Oh wait; That's not a cart; but the shadow of his mirror1 How did he accomplish that!
That's a water reflection of his mirror containing his own face against an unrevealed piece of sky that RJN has put forth a Quiz challenge.

Anyone figured it out yet :?:
What's reflected in the mirror is trivial to identify, a very well known dusty section of the Milky Way lying between Sagittarius and Scorpius... and in 2019, hosting Jupiter, the bright "star" in the lower right of the mirror. The section of the sky seen in the reflection of the reflection, however, is not so simple. It's clearly almost directly behind the guy's head, so not far from what we see in the upper right of the APOD. But it's pretty distorted to pick out more than that.
Last edited by Chris Peterson on Mon Sep 13, 2021 8:34 pm, edited 1 time in total.
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by Ann » Mon Sep 13, 2021 8:27 pm

Doubly reflected sky APOD September 13 2021.png

This is what I can see in the doubly reflected image:

1: A very blue star. Note that almost all the stars in the doubly reflected image looks more or less bluish, but this one stands out. I'd say that the light that reaches us from this star is at least as blue as Vega's and probably bluer.

2) This star looks almost completely non-blue. Since we definitely expect to see some yellow or orange stars in a patch of sky as big as the doubly reflected image appears to be, I'd say that this is a yellow or orange star, most likely of spectral class K. But other spectral classes are also possible.

3) This looks like a pretty big fat dark dust cloud to me.

4) This looks like a patch of clear galactic sky where myriads of Milky Way stars are looking down on us. Yeah! I know that's his head. But look behind him!

So where in the sky are we? D'uh! I really don't know.

Ann
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by johnnydeep » Mon Sep 13, 2021 8:43 pm

Ann wrote:
Mon Sep 13, 2021 8:27 pm
Doubly reflected sky APOD September 13 2021.png
[/clear


This is what I can see in the doubly reflected image:

1: A very blue star. Note that almost all the stars in the doubly reflected image looks more or less bluish, but this one stands out. I'd say that the light that reaches us from this star is at least as blue as Vega's and probably bluer.

2) This star looks almost completely non-blue. Since we definitely expect to see some yellow or orange stars in a patch of sky as big as the doubly reflected image appears to be, I'd say that this is a yellow or orange star, most likely of spectral class K. But other spectral classes are also possible.

3) This looks like a pretty big fat dark dust cloud to me.

4) This looks like a patch of clear galactic sky where myriads of Milky Way stars are looking down on us. Yeah! I know that's his head. But look behind him!

So where in the sky are we? D'uh! I really don't know.

Ann
I'm probably being obtuse if not downright dumb but why shouldn't we be seeing exactly the same piece of sky in the mirror below the red line as we see above the red line? (Though less of an area of it, and possibly overlaid on the direct reflection of the sky.) We clearly see the man in apparently the same pose both above and below the red line.

reflected starry sky.JPG
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by Chris Peterson » Mon Sep 13, 2021 9:06 pm

johnnydeep wrote:
Mon Sep 13, 2021 8:43 pm
I'm probably being obtuse if not downright dumb but why shouldn't we be seeing exactly the same piece of sky in the mirror below the red line as we see above the red line? (Though less of an area of it, and possibly overlaid on the direct reflection of the sky.) We clearly see the man in apparently the same pose both above and below the red line.
We clearly see a very different view of the man's face in the two reflections! Look again.

Try drawing a little ray diagram from the side, and you'll quickly see that the light is following two different paths.
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by johnnydeep » Mon Sep 13, 2021 9:23 pm

Chris Peterson wrote:
Mon Sep 13, 2021 9:06 pm
johnnydeep wrote:
Mon Sep 13, 2021 8:43 pm
I'm probably being obtuse if not downright dumb but why shouldn't we be seeing exactly the same piece of sky in the mirror below the red line as we see above the red line? (Though less of an area of it, and possibly overlaid on the direct reflection of the sky.) We clearly see the man in apparently the same pose both above and below the red line.
We clearly see a very different view of the man's face in the two reflections! Look again.

Try drawing a little ray diagram from the side, and you'll quickly see that the light is following two different paths.
I'm saying the man's face in the mirror above the line appears to be the same as his face below the line. (He says, getting more confused by this picture by the post :( )
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by Chris Peterson » Mon Sep 13, 2021 9:28 pm

johnnydeep wrote:
Mon Sep 13, 2021 9:23 pm
Chris Peterson wrote:
Mon Sep 13, 2021 9:06 pm
johnnydeep wrote:
Mon Sep 13, 2021 8:43 pm
I'm probably being obtuse if not downright dumb but why shouldn't we be seeing exactly the same piece of sky in the mirror below the red line as we see above the red line? (Though less of an area of it, and possibly overlaid on the direct reflection of the sky.) We clearly see the man in apparently the same pose both above and below the red line.
We clearly see a very different view of the man's face in the two reflections! Look again.

Try drawing a little ray diagram from the side, and you'll quickly see that the light is following two different paths.
I'm saying the man's face in the mirror above the line appears to be the same as his face below the line. (He says, getting more confused by this picture by the post :( )
I disagree completely. In the mirror, we're looking up at his chin from below it. In the water, we're looking almost directly into his face. I'd say there's at least a 30° difference in the viewing angles there.
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by neufer » Mon Sep 13, 2021 10:40 pm

Chris Peterson wrote:
Mon Sep 13, 2021 4:14 pm
neufer wrote:
Mon Sep 13, 2021 3:59 pm
orin stepanek wrote:
Mon Sep 13, 2021 3:38 pm

Oh wait; That's not a cart; but the shadow of his mirror1 How did he accomplish that!
That's a water reflection of his mirror containing his own face against an unrevealed piece of sky that RJN has put forth a Quiz challenge. Anyone figured it out yet :?:
What's reflected in the mirror is trivial to identify, a very well know dusty section of the Milky Way lying between Sagittarius and Scorpius... and in 2019, hosting Jupiter, the bright "star" in the lower right of the mirror. The section of the sky seen in the reflection of the reflection, however, is not so simple. It's clearly almost directly behind the guy's head, so not far from what we see in the upper right of the APOD. But it's pretty distorted to pick out more than that.
johnnydeep wrote:
Mon Sep 13, 2021 8:43 pm

... why shouldn't we be seeing exactly the same piece of sky in the mirror below the red line as we see above the red line? (Though less of an area of it, and possibly overlaid on the direct reflection of the sky.) We clearly see the man in apparently the same pose both above and below...
Both the mirror and its reflection are picking up a vertical axis parallel to & slightly to the left of the left edge of the APOD (& "almost" perpendicular to the SMC/LMC axis). This axis (lies a little further left of the SMC than the SMC lies to left of the LMC and) passes past zenith through The Pipe Nebula. The mirror image is of an upside down Pipe Nebula. The reflected mirror image is of an upright asterism of comparable size but somewhat further past zenith through the same vertical axis.
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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by Ann » Tue Sep 14, 2021 4:47 am

neufer wrote:
Mon Sep 13, 2021 10:40 pm
Both the mirror and its reflection are picking up a vertical axis parallel to & slightly to the left of the left edge of the APOD (& "almost" perpendicular to the SMC/LMC axis). This axis (lies a little further left of the SMC than the SMC lies to left of the LMC and) passes past zenith through The Pipe Nebula. The mirror image is of an upside down Pipe Nebula. The reflected mirror image is of an upright asterism of comparable size but somewhat further past zenith through the same vertical axis.
Let me see if I got this straight.

Milky Way axis through the Pipe Nebula.png

Should we imagine a vertical line through the Pipe Nebula, a line that is almost perpendicular to the axis between the LMC and the SMC? And what we see in the doubly reflected mirror image should lie somewhere along this perpendicular axis through the Pipe Nebula?

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Re: APOD: Night Sky Reflected (2021 Sep 13)

Post by orin stepanek » Tue Sep 14, 2021 12:43 pm

Why do we see brighter stars in the lake and mirror than in the sky?
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