APOD: Milky Way above Atacama Salt Lagoon (2014 Sep 16)

[APOD Robot]

Milky Way above Atacama Salt Lagoon

Explanation: Galaxies, stars, and a serene reflecting pool combine to create this memorable land and skyscape. The featured panorama is a 12-image mosaic taken last month from the Salar de Atacama salt flat in northern Chile. The calm water is Laguna Cejar, a salty lagoon featuring a large central sinkhole. On the image left, the astrophotographer's fiancee is seen capturing the same photogenic scene. The night sky is lit up with countless stars, the Large and Small Magellanic Cloud galaxies on the left, and the band of our Milky Way galaxy running diagonally up the right. The Milky Way may appear to be causing havoc at the horizon, but those are just the normal lights of a nearby town.

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[geckzilla]

Heh, the two lights and hunched over photographer and tripod on the left I mistook for an animal with glowing eyes.

[Beyond]

You wouldn't catch me as close to a sinkhole as the photographer's fiancé is. That's just too dangerous!!

[Startreader]

Heh, the two lights and hunched over photographer and tripod on the left I mistook for an animal with glowing eyes.

It *IS* an animal with two eyes. It's a species called "Fiancée". They tend to be wonderful, beautiful and even better after they metamorphose.

This is a truly gorgeous image, many thanks to APoD and the photographers. We live in a spectacularly lovely part of the cosmos.

[Ann]

Heh, the two lights and hunched over photographer and tripod on the left I mistook for an animal with glowing eyes.

Looks like the cousin of E.T., twice removed.

Ann

[alex.tudorica]

You wouldn't catch me as close to a sinkhole as the photographer's fiancé is. That's just too dangerous!!

It wasn't so dangerous as it might seem, although I admit that when I realized what it is, deep in the night, I suddenly felt a bit uneasy Especially when I remembered reading that it's 40m (~120ft) deep! The scale is a bit misleading maybe, she's probably 20-30 m away from the edge of the sinkhole.

[hlwelborn]

Images of broken light
Which dance before me like a million eyes
They call me on and on across the universe......

[down to earth]

Ahhh today's APOD is so awesome!! Love the view.

[Ron-Astro Pharmacist]

Chile has some of the best sky's while also having some of the flattest places on Earth. When they have a layer of water covering the salt flats they become quite reflective. Should have a bright future too with all the lithium dissolved in the ground underneath.

[Boomer12k]

That is an awesome shot.
That is an impressive stretch of sky!!! and then to have a convenient Reflecting Pond....
Look at all the stars that are outside the Galactic Plane...

:---[===] *

[DavidLeodis]

Such photos fill me with awe and wonder . What an amazing sight it must have been to the naked eye. It's a shame that increasing global light pollution is making it ever harder to see such scenes. Where I am it is a good night if I can readily see more than just a few of the brightest stars even on clear nights!

[Guest]

> Such photos fill me with awe and wonder

Whenever I see a photograph like this of the horizon that has no great reduction of star brightness near the horizon I immediately think "fake". The number of such fakes is increasing.

To see a realistic reduction in star brightness near the horizon see more recent http://apod.nasa.gov/apod/ap140920.html

[geckzilla]

It's not fake. The atmosphere just looks skinnier in this one because of the wide angle. Atmospheric and lighting conditions also vary. Please do not slander the photographer with vague, unsubstantiated accusations like this.

[alter-ego]

> Such photos fill me with awe and wonder

Whenever I see a photograph like this of the horizon that has no great reduction of star brightness near the horizon I immediately think "fake". The number of such fakes is increasing.

To see a realistic reduction in star brightness near the horizon see more recent http://apod.nasa.gov/apod/ap140920.html

The atmospheric transparency does degrade toward the horizon as light travels through more air mass and leads to brighter limiting magnitude (referred to as atmospheric extinction). This clarity directly correlates to sky quality, i.e. darker skies typically have better quality toward the horizon. Your experience with sky transparency, which is strongly affected by moisture, dust and pollution content, might lead you question today's image but I strongly doubt this image has been doctored in any way to enhance the sky quality near the horizon.

With that said, composite images are sometimes created that paste in a beautiful sky on a landscape. These have identifiable traces of an unreal sky. As long as they aren't falsely claiming to be a "true" image, I treat them as art. Anyway, today's image shows what is a very nice, clear sky.
By the way, extinction is evident, just not to the level you're referring to.

[geckzilla]

Oooh, getting all fancy with words like extinction and limiting magnitude.

[alter-ego]

Oooh, getting all fancy with words like extinction and limiting magnitude.

Necessary accoutrements in the esoteric realm of astronomical vernacular and descriptive precision.
Plus I gotta use'm when I got da chance!

[alex.tudorica]

The atmospheric transparency does degrade toward the horizon as light travels through more air mass and leads to brighter limiting magnitude (referred to as atmospheric extinction). This clarity directly correlates to sky quality, i.e. darker skies typically have better quality toward the horizon. Your experience with sky transparency, which is strongly affected by moisture, dust and pollution content, might lead you question today's image but I strongly doubt this image has been doctored in any way to enhance the sky quality near the horizon.

With that said, composite images are sometimes created that paste in a beautiful sky on a landscape. These have identifiable traces of an unreal sky. As long as they aren't falsely claiming to be a "true" image, I treat them as art. Anyway, today's image shows what is a very nice, clear sky.
By the way, extinction is evident, just not to the level you're referring to.

Thanks for the detailed explanation As you say, the skies in Chile are quite special, and even more so in the Atacama desert. Extinction increases greatly with the amount of water vapour present in the air and Atacama is rather famous for being the driest hot desert in the world. Regarding doctoring images - you're again right - besides contrast, white balance, some noise reduction and a little bit of sharpening, this image has not been modified in any way. I could push it quite a bit as it's a 12-frame panorama, so the noise doesn't really show up when the image is downsized so much. Nevertheless, I can provide the individual frames (and even the raw's, if it comes to that) in order to prove that this is not a "fake" image in the way described by our guest here.

I was actually expecting people to say that it's "fake" because of the sinkhole (and that's the main reason for which I marked it there). It does look like the reflection of some mountains that don't show up in the final picture, right? But if you have a look at this panorama: https://www.flickr.com/photos/27891676@N05/15252272412/, which I took only a few minutes before the APOD image, I think it's much clearer. In this last panorama it's also quite interesting to see how the wind settles down during the shots - in the beginning the water is all fuzzy, while towards the end it looks like almost a perfect mirror. And the extinction still is incredibly low.

[Indigo_Sunrise]

But if you have a look at this panorama: https://www.flickr.com/photos/27891676@N05/15252272412/

Good lord! That image looks almost like it was taken during the day! And I mean that as a compliment, since it's so detailed and beautiful. Absolutely the highest kudos to you, Alex. Very awesome!