Offline Norr

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Re: No Stars
« Reply #40 on: October 12, 2016, 03:40:21 AM »
Quick answer: The dense atmosphere of earth means little to no exposure time because the light is being reflected through the gasses.

 In space where there is very little gas in any given area, the camera must focus longer to get the same amount of light entering it. If there was a thick medium for the light to travel through it would be easier and would take far less time.
 
 The fact that we can see stars through the atmosphere of earth is simple to explain: Earth has been getting billions of years of light exposure.

Sorry, but no. The presence of an atmosphere does not make a camera focus faster. Less atmosphere means MORE light from the stars reaches the camera, not less. The real explanation has been given several times on this thread. It has to do with brightness of the stars relative to the thing you are photographing.


Seriously I just repeated what Phil Plait said. That's a bit worrisome to be honest.

Re: No Stars
« Reply #41 on: October 12, 2016, 04:05:23 AM »
Quick answer: The dense atmosphere of earth means little to no exposure time because the light is being reflected through the gasses.

 In space where there is very little gas in any given area, the camera must focus longer to get the same amount of light entering it. If there was a thick medium for the light to travel through it would be easier and would take far less time.
 
 The fact that we can see stars through the atmosphere of earth is simple to explain: Earth has been getting billions of years of light exposure.

Sorry, but no. The presence of an atmosphere does not make a camera focus faster. Less atmosphere means MORE light from the stars reaches the camera, not less. The real explanation has been given several times on this thread. It has to do with brightness of the stars relative to the thing you are photographing.


Seriously I just repeated what Phil Plait said. That's a bit worrisome to be honest.

Source? I suspect you just misunderstood him. In general, this part is technically true: "camera must focus longer to get the same amount of light entering it". However, that is because there is more AMBIENT light, not more star light. If you want to look at the stars, ambient light is bad.

Compare stargazing in a big city to out in the woods. Thicker atmosphere (smog) + more ambient light = fewer stars.

Offline Norr

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Re: No Stars
« Reply #42 on: October 12, 2016, 04:13:45 AM »
Quick answer: The dense atmosphere of earth means little to no exposure time because the light is being reflected through the gasses.

 In space where there is very little gas in any given area, the camera must focus longer to get the same amount of light entering it. If there was a thick medium for the light to travel through it would be easier and would take far less time.
 
 The fact that we can see stars through the atmosphere of earth is simple to explain: Earth has been getting billions of years of light exposure.

Sorry, but no. The presence of an atmosphere does not make a camera focus faster. Less atmosphere means MORE light from the stars reaches the camera, not less. The real explanation has been given several times on this thread. It has to do with brightness of the stars relative to the thing you are photographing.


Seriously I just repeated what Phil Plait said. That's a bit worrisome to be honest.

Source? I suspect you just misunderstood him. In general, this part is technically true: "camera must focus longer to get the same amount of light entering it". However, that is because there is more AMBIENT light, not more star light. If you want to look at the stars, ambient light is bad.

Compare stargazing in a big city to out in the woods. Thicker atmosphere (smog) + more ambient light = fewer stars.

Will be hard to give you the exact source right now. I'm on my phone, Matthew took out the power in the area. It was on a Crash Course Astronomy episode I believe. I'll source it as soon as I can if you still want it by then.

  Yes I probably did misunderstand him. I tend to research far too much at once so things get crossed.

Re: No Stars
« Reply #43 on: July 07, 2017, 01:56:36 AM »
That's not a real photo.
Irrelevant, the OP was asking why don't we see stars in NASA's pictures containing sunlit planet, but in fact the Blue Marble does contain some stars when zoomed in. And if the Blue Marble was a fake, why the heck would they even bother put the stars that are hard to see anyway? They could just say no stars because low exposure.

Here's some from Roscosmos, the Russian space agency. http://gizmodo.com/5787176/this-is-the-moon-and-the-earth-like-you-have-never-seen-them-before.

Offline 3DGeek

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Re: No Stars
« Reply #44 on: July 10, 2017, 09:32:39 PM »
That's not a real photo.
Irrelevant, the OP was asking why don't we see stars in NASA's pictures containing sunlit planet, but in fact the Blue Marble does contain some stars when zoomed in. And if the Blue Marble was a fake, why the heck would they even bother put the stars that are hard to see anyway? They could just say no stars because low exposure.

Look I'm an avide RE'er...and I'll be the first to admit that the "Blue Marble" is not a simple straightforward photograph.   "fake" is a strong word.   It's a composite image (which NASA do not deny) of many photos put together to make a beautiful representation of our planet.

It would be impossible to get a photo this good in reality because the orientation of the sun to the outer edges of the sphere would be shaded into darkness.

Trouble is that if you make a composite of photos taken at different times - the clouds wouldn't match up - so those were layered on afterwards.

So - yeah - we can't rely on "The Blue Marble" to prove a darned thing.   There is no mysterious secrecy about this - it's a composite image.

So it's reasonable to say that the stars in it were added for artistic benefits too.

So please stop posting it as some kind of "proof" that RE is true - and for the FE'ers - why would NASA admit that it was a composite image if they were trying to cover something up.

This picture is NOT evidence either way.
« Last Edit: July 13, 2017, 03:00:49 PM by 3DGeek »
Hey Tom:  What path do the photons take from the physical location of the sun to my eye at sunset?

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Offline Dither

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Re: No Stars
« Reply #45 on: July 12, 2017, 12:57:35 AM »
It would be impossible to get a photo this good in reality because the orientation of the sun to the outer edges of the sphere would be shaded into darkness.

Then please show us that photo shaded into darkness with the supposed distance,
How about also taking some quick snaps from the many long distance spacecraft they supposedly send out.


 
A lie will make it around the world before the truth has time to put on its shoes.

Re: No Stars
« Reply #46 on: July 12, 2017, 03:58:16 AM »
It would be impossible to get a photo this good in reality because the orientation of the sun to the outer edges of the sphere would be shaded into darkness.

Then please show us that photo shaded into darkness with the supposed distance,
How about also taking some quick snaps from the many long distance spacecraft they supposedly send out.
Sure thing! Some from earlier this year! NOAA updates the image of Earth posted here every single day from their GOES-16 satellite with a multitude of filters available. It might not be exactly as 3DGeek described, but I believe at least one of the images in that first one was taken from a position directly between the Sun and Earth, and thus the dark side is extremely minimal. Here's another, along with a direct link at the bottom to the DISCOVR satellite page with more information on that specific satellite.

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Offline Jura-Glenlivet

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Re: No Stars
« Reply #47 on: July 12, 2017, 07:35:38 AM »
Here's a good one, not NASA, the Russian Elektro-L.

« Last Edit: July 12, 2017, 07:37:57 AM by Jura-Glenlivet »
Just to be clear, you are all terrific, but everything you say is exactly what a moron would say.

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Offline Rounder

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Re: No Stars
« Reply #48 on: July 13, 2017, 05:57:20 AM »
How about also taking some quick snaps from the many long distance spacecraft they supposedly send out.

Some probes actually have done what you suggest.  A lot of probes, in fact.  Messenger did it on its way to Mercury, as did JAXA on its way to Venus.  The Lunar Reconnaissance Orbiter and the Mars Reconnaissance Orbiter have both done this from their final destinations.  Rosetta took Earth crescent photos on multiple gravity-assist passes of Earth on its way to the comet it observed (crescent because Rosetta was approaching Earth from higher orbit, which put it on the night side of the planet).  At least two Jupiter probes (Galileo and Juno) have taken Earth photos as they flew past us for gravity assist maneuvers.  Same for outer planet missions like Cassini (Saturn) and New Horizons (Pluto and Kuiper Belt Object 2014 MU69)
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Offline 3DGeek

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Re: No Stars
« Reply #49 on: July 13, 2017, 03:21:14 PM »
Here's a good one, not NASA, the Russian Elektro-L.


That's a very beautiful image.  There are lots of features of it that blue-marble doesn't have.

Look, for example at the ocean just above Madagasgar - off the East coast of Africa.  There is a whiter patch.  That's a reflection of the sun - think about the angle of incidence and angle of reflection off of the round surface - and that the sun must be over to the left - and there you have it.  It's not a nice perfect reflection because the ocean is full of waves - and that diffuses and softens the image.

Look along the 'terminator' (the line between day and night) - you can see the clouds look 'bumpier' - but that's because the light is landing on them edge-on and the higher bits are casting shadows onto the lower bits, giving a more three-dimensional appearance.

You can even see subtle red tints on the edges of the clouds to the west of the terminator - and where the tops of the highest clouds are still catching the sunlight on the east of the terminator (especially around the south pole)...and those clouds are tinted yellow because the sunlight is passing through a great deal of atmosphere at that angle, and so the scattering of the blue light that makes the sky blue has leached out blue light from the white sunlight - leaving it yellow in color.

The swirl of clouds at the bottom-center of the picture is a spinning in the direction that southern-hemisphere coriolis effect would cause it to swirl.

The eastern edge of Lake Tanganyika is outlined in white cloud - actually, it's fog - which is a daily event there - it provides just enough mid-morning moisture for "air plants" to grow on trees there without needing roots.

If you look on the very tip of the arabian peninsula - on the east coast - you can see a tiny puff of white cloud, which is where the evaporation from the vast artificial irrigation systems of Dubai has drifted over the mountains of Jebel al Harim - been pushed up to higher altitudes and in condensing into cloud.

So if this is a fake it's a truly spectacularly good one - someone took a LOT of trouble to make the details just picture perfect, and to reproduce exactly what you'd expect to see on a round earth...or maybe it's not a fake after all!


Hey Tom:  What path do the photons take from the physical location of the sun to my eye at sunset?