APOD: Firefall by Moonlight (2017 Jun 08)

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APOD: Firefall by Moonlight (2017 Jun 08)

Post by APOD Robot » Thu Jun 08, 2017 4:12 am

[img]https://apod.nasa.gov/apod/calendar/S_170608.jpg[/img] Firefall by Moonlight

Explanation: On certain dates in February, an elusive firefall can be spotted at sunset in Yosemite National Park, when the weather cooperates and the direction to the setting Sun is just right. Often photographed from vantage points below, at the right moment the park's seasonal Horsetail Fall is isolated in the shadows of the steep walls of El Capitan but still illuminated with rays of sunlight reflected by the angled rockface directly behind the flow, briefly giving the waterfall a dramatic fiery appearance. The Horsetail firefall is more rarely photographed at moonset under a starry night sky, though. Even more elusive by moonlight, the firefall effect can also be seen when skies are clear and a bright Moon sets at the right direction along the western horizon. Skies were clear and stars were shining for this well-planned photograph of the Horsetail firefall lit by a gibbous Moon setting in the early morning hours of May 9.

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De58te
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Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by De58te » Thu Jun 08, 2017 5:57 am

Beautiful picture. But is it Firefall by Moonlight or Firefall by Sunset light? Because the last link of Firefall by Moonlight looks exactly the same complete with the stars in May in exactly the same position.

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Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by Boomer12k » Thu Jun 08, 2017 6:07 am

De58te wrote:Beautiful picture. But is it Firefall by Moonlight or Firefall by Sunset light? Because the last link of Firefall by Moonlight looks exactly the same complete with the stars in May in exactly the same position.
This is the Moonlit one... in May... the beginning it seems is a introductory description of the Sunset lit falls, in February....

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firstmagnitude

Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by firstmagnitude » Thu Jun 08, 2017 6:34 am

What constellations are in this composite image...if any?

RBANDREO

Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by RBANDREO » Thu Jun 08, 2017 7:19 am

firstmagnitude wrote:What constellations are in this composite image...if any?
Best,
Rogelio

RBANDREO

Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by RBANDREO » Thu Jun 08, 2017 7:21 am

firstmagnitude wrote:What constellations are in this composite image...if any?
Oh and it's not a composite. It's a 2 panes mosaic, both panes same settings and exposure.

Thanks,
Rogelio

Catalina

Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by Catalina » Thu Jun 08, 2017 5:25 pm

This is a lovely image. Are the colors manipulated to make it appear more "firefall"-like? I'm wondering why the mid and background trees appear to be bathed in an orange light as if it were sunset? Does a moonset often have an orange light for the same reason as a sunset would?

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Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by geoffrey.landis » Thu Jun 08, 2017 6:02 pm

I'm somewhat puzzled about this image. The sky reflected in the river (bottom left) is brighter than the unreflected sky. I can't quite figure that out.

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Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by bystander » Thu Jun 08, 2017 6:40 pm

geoffrey.landis wrote:I'm somewhat puzzled about this image. The sky reflected in the river (bottom left) is brighter than the unreflected sky. I can't quite figure that out.

I think it is probable that the portion of the sky you see reflected is hidden by the trees.
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edibleplantguy

Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by edibleplantguy » Thu Jun 08, 2017 7:01 pm

I am skeptical that this image is in any meaningful way - real. I know of nowhere on Earth (spelled frontwards) where you can see anywhere near this many stars before the disk of the setting sun is set; and a long exposure will brighten the background sky - not the stars.

RBANDREO

Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by RBANDREO » Thu Jun 08, 2017 7:57 pm

Catalina wrote:This is a lovely image. Are the colors manipulated to make it appear more "firefall"-like? I'm wondering why the mid and background trees appear to be bathed in an orange light as if it were sunset? Does a moonset often have an orange light for the same reason as a sunset would?
Colors are real, no color has been "painted", added or modified. Color saturation has been increased, though. Yes, moonset casts similar hues as sunset. It is, after all, sunlight, just reflected on the Moon, so it's much dimmer but the same laws apply. Have you not ever seen a setting moon or pictures of it? Depending on a number of factors it can be extremely reddish in color. Thanks!

Best,
Rogelio

RBANDREO

Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by RBANDREO » Thu Jun 08, 2017 8:04 pm

geoffrey.landis wrote:I'm somewhat puzzled about this image. The sky reflected in the river (bottom left) is brighter than the unreflected sky. I can't quite figure that out.
That's actually not unusual at all, but I can see why it could be puzzling. You'd just need light to hit the water from a direction other than the reflected sky to produce highlights on the surface - that being just one of many way this can happen. Do some local contrast adjustments and the effect is increased even more, of course.

Thanks,
Rogelio

RBANDREO

Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by RBANDREO » Thu Jun 08, 2017 8:10 pm

edibleplantguy wrote:I am skeptical that this image is in any meaningful way - real. I know of nowhere on Earth (spelled frontwards) where you can see anywhere near this many stars before the disk of the setting sun is set; and a long exposure will brighten the background sky - not the stars.
If you read the title of the APOD, it says Firefall by Moonlight. Moonlight, not a setting sun. It wasn't even twilight (but close!). The whole text should clarify everything even more, and the article it links will settle it. Thing is, if the image wasn't real, the text would also say so, that's a good place to start when something doesn't click in our head, have a look, read it, and let me know if you have any other questions.

Thanks,
Rogelio

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Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by rstevenson » Thu Jun 08, 2017 11:18 pm

That's a beautiful picture Rogelio. Thanks for sharing your work with us.

Rob

KenR

Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by KenR » Fri Jun 09, 2017 4:57 am

On the average, how many time a year is the alignment correct to get such a picture, assuming the waterfall is flowing?

RBANDREO

Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by RBANDREO » Fri Jun 09, 2017 5:14 am

KenR wrote:On the average, how many time a year is the alignment correct to get such a picture, assuming the waterfall is flowing?
With moonlight, between 0 and 2~3 nights per year.

Best,
Rogelio

Arthight

Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by Arthight » Fri Jun 09, 2017 1:30 pm

Years ago (1960's the firefall was a nightly event, but from Glacier Point. It was easily visible in the meadow. They discontinued for years due to the fire danger. I'm glad to see they are doing it again. It is spectacular to watch in person.

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Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by BDanielMayfield » Fri Jun 09, 2017 1:52 pm

Arthight wrote:Years ago (1960's the firefall was a nightly event, but from Glacier Point. It was easily visible in the meadow. They discontinued for years due to the fire danger. I'm glad to see they are doing it again. It is spectacular to watch in person.
Wasn't that when they actually polluted the falls every night by throwing burning coals in at the top of the falls? This photo is just naturally lit by moonlight as well explained in the above discussion.
Just as zero is not equal to infinity, everything coming from nothing is illogical.

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Re: APOD: Firefall by Moonlight (2017 Jun 08)

Post by warmingwarmingwarming » Fri Jun 09, 2017 2:41 pm

"And I think to myself, 'what a wonderful world.' Louis.

With so many wonderful 'scenes' in the world it's no wonder mankind is a curiousity-powered creature .. seeking, seeking, seeking.
I think I think, though I'm not sure if I all the thoughts I think I think, or if they come to me from .. goodness knows where. :)