APOD: Cerro Tololo Trails (2016 Oct 22)

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APOD: Cerro Tololo Trails (2016 Oct 22)

Postby APOD Robot » Sat Oct 22, 2016 4:07 am

Image Cerro Tololo Trails

Explanation: Early one moonlit evening car lights left a wandering trail along the road to the Chilean Cerro Tololo Inter-American Observatory. Setting stars left the wandering trails in the sky. The serene view toward the mountainous horizon was captured in a telephoto timelapse image and video taken from nearby Cerro Pachon, home to Gemini South. Afforded by the mountaintop vantage point, the clear, long sight-line passes through layers of atmosphere. The changing atmospheric refraction shifts and distorts the otherwise steady apparent paths of the stars as they set. That effect also causes the distorted appearance of Sun and Moon as they rise or set near a distant horizon.

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Ann
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Re: APOD: Cerro Tololo Trails (2016 Oct 22)

Postby Ann » Sat Oct 22, 2016 4:14 am

I note that all the star trails are red. :shock:

That's a bonanza of red giant stars! :wink:

Perhaps this might have been an opportunity to say something about the reddening effects of the Earth's atmosphere, or possibly how the reddening of stars could be a photographic or post-production effect. Maybe...?

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Re: APOD: Cerro Tololo Trails (2016 Oct 22)

Postby geckzilla » Sat Oct 22, 2016 4:30 am

Ann wrote:Perhaps this might have been an opportunity to say something about the reddening effects of the Earth's atmosphere, or possibly how the reddening of stars could be a photographic or post-production effect. Maybe...?

Yes. It's definitely atmospheric reddening.
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Re: APOD: Cerro Tololo Trails (2016 Oct 22)

Postby Boomer12k » Sat Oct 22, 2016 6:19 am

Interesting...Stars wiggle on the horizon, because of turbulence...

Looks like South Mountain in Phoenix, on a Friday Night...

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Last edited by Boomer12k on Sat Oct 22, 2016 6:21 am, edited 1 time in total.

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Re: APOD: Cerro Tololo Trails (2016 Oct 22)

Postby Boomer12k » Sat Oct 22, 2016 6:20 am

Do stars give a "green flash"?

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Re: APOD: Cerro Tololo Trails (2016 Oct 22)

Postby geckzilla » Sat Oct 22, 2016 7:47 am

Boomer12k wrote:Do stars give a "green flash"?

Light doesn't behave differently if it's coming from the Sun or a distant star, so presumably they can and do and it's just a matter of capturing it.
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Re: APOD: Cerro Tololo Trails (2016 Oct 22)

Postby darksky2500@gmail.com » Sat Oct 22, 2016 12:40 pm

This is the first time I've ever seen that degree of atmospheric distortion of stars near the horizon. I'm adding a photo like this to my own bucket list. Incredibly artistic capture with a nice scientific talking point.

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Re: APOD: Cerro Tololo Trails (2016 Oct 22)

Postby Chris Peterson » Sat Oct 22, 2016 2:11 pm

Boomer12k wrote:Do stars give a "green flash"?

Not exactly a "flash", more like a "shift". If fact, the phenomenon that causes the green flash is much more obvious in stars. If you image a star near the horizon at high magnification, it will not appear as a point, but as a streak showing the entire spectrum. That's because the dispersion of the atmosphere acts just like a prism.

People who need to do imaging low in the sky sometimes employ a prism in their optical system to undo the atmospheric dispersion. Here's an example.
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Re: APOD: Cerro Tololo Trails (2016 Oct 22)

Postby Boomer12k » Sun Oct 23, 2016 12:34 am

Reminds me of playing... Missile Command on the C64...

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Re: APOD: Cerro Tololo Trails (2016 Oct 22)

Postby geckzilla » Sun Oct 23, 2016 12:57 am

It figures if you want to know about atmospheric dispersion correctors, you go to atmospheric-dispersion-corrector.com.
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