When are the stars no longer visible?

[Capt. Speirs]

Rpobably the wrong forum, but here goes...

When you look at pictures from the moon, you see no stars (no atmosphere), when do you no longer see the stars leaving earth? At how many kilometers altitude is the atmosphere gone? In Orbiter you always see the stars, that (IMHO) takes away from the experience. I think at LEO from the Shuttle you should not be able to see the stars.:blink:

 

[ryan]

Light from the sun blocks the stars light which is more duller than the sun, gees its pretty simple and i think its explained at Wiki somewhere, remember do your research before you post.
Thanks.
Ryan.

 

[SpaceNut]

When you look at the pictures from the moon, it's not the presence or absence of an atmosphere that determines weather you can see the stars, but rather the exposure settings on the camera. If the camera were to be set with a long enough exposure to see the stars, the rest of the image would be overexposed. Also, if you look closely at some of the higher resolution moon images available, you will see a star or two here and there, the ones with a low enough magnitudes to have been bright enough to show up on the picture. The only effect the atmosphere of the earth has on stars is to make them twinkle. This is due to high speed winds at higher altitudes causing the light to be bent momentarily, producing the twinkle effect you see here on earth. On the moon, the stars would be easily visible to you, but they wouldn't twinkle.

As far as the 'end' of the atmosphere, it's not really a set point, rather, the density of the air gets lower and lower until atmospheric pressure is 0. That happens at about 100 kilometers (60 miles) up. You'd begin to have trouble breathing much above 2 miles up though.

 

[Capt. Speirs]

When you look at the pictures from the moon, it's not the presence or absence of an atmosphere that determines weather you can see the stars, but rather the exposure settings on the camera. If the camera were to be set with a long enough exposure to see the stars, the rest of the image would be overexposed. Also, if you look closely at some of the higher resolution moon images available, you will see a star or two here and there, the ones with a low enough magnitudes to have been bright enough to show up on the picture. The only effect the atmosphere of the earth has on stars is to make them twinkle. This is due to high speed winds at higher altitudes causing the light to be bent momentarily, producing the twinkle effect you see here on earth. On the moon, the stars would be easily visible to you, but they wouldn't twinkle.

As far as the 'end' of the atmosphere, it's not really a set point, rather, the density of the air gets lower and lower until atmospheric pressure is 0. That happens at about 100 kilometers (60 miles) up. You'd begin to have trouble breathing much above 2 miles up though.

So if I get this right, when the shuttle is in LEO and you look out the window, you will see 100's of thousands stars or more. That would make Orbiter's stars and planets display accurate, correct?


-----Posted Added-----

Light from the sun blocks the stars light which is more duller than the sun, gees its pretty simple and i think its explained at Wiki somewhere, remember do your research before you post.
Thanks.
Ryan.

Wiki is not the end all to information.

Ryan, speaking of simple, you didn't know which button to press for screenshot which is clearly in your operating system's manual that you could have researched. Just thought I would fire one back.

http://orbiter-forum.com/showthread.php?p=12278#post12278 page 9

 

[ryan]

Take my information into consideration, can you see stars in day? the sun is brighter than the stars you eyes cant adjust to the faint glow of the stars, neither can cameras. Same goes on the moon and especially in LEO where the glow of the lit up atmosphere does what white snow does to your eyes, it blocks out things, like when snow reflects sunlight and the atmoshperes light blocks out the glow of the stars, the only way to see them is through a telescope on board or fly through the night side. Sadly orbiter has not yet the capbility to adjust from no stars and stars in one orbit around the earth.


-----Posted Added-----

So if I get this right, when the shuttle is in LEO and you look out the window, you will see 100's of thousands stars or more. That would make Orbiter's stars and planets display accurate, correct?


-----Posted Added-----




Wiki is not the end all to information.

Ryan, speaking of simple, you didn't know which button to press for screenshot which is clearly in your operating system's manual that you could have researched. Just thought I would fire one back.

http://orbiter-forum.com/showthread.php?p=12278#post12278 page 9

I posted that when? 3 or 4 months ago, probaply back then i was still learning how to get off the ground in orbiter.

 

[Hashy]

Why bother asking a question, if you've already researched it, and know all the answers?

 

[tblaxland]

Sadly orbiter has not yet the capbility to adjust from no stars and stars in one orbit around the earth.

This is not really an Orbiter issue, it is more of an issue of the limited dynamic range of your monitor.

 

[Sherrif of Nottingham]

Why bother asking a question, if you've already researched it, and know all the answers?

Sometimes you may only know parts of an answer, you just want to know the whole thing while your at it.

I did a short google image search and found this, lol:

I did not write this, this is SOO from that site;

For thirty seven years now the debate has raged; did the United States put men on the moon or did they perpetuate a grand hoax and film the event on earth as a propaganda campaign against the Soviet Union?
For examples we will start with the first large claim by the conspirists; that despite the airless vacuum of the lunar environment there were no stars showing in the photographs. The makers of the Hasselblad cameras used have tried to explain that in order to photograph the astronauts in such a glaring environment your exposure time would of necessity be too short to pick up the minute light of background stars. They insist that the only reason the Earth showed up was because of the intensity of the light reflected from it and its proximity to the moon.

Contributed by Wm. Douglas Mefford and Copyright © 2007 True Ghost Tales all rights reserved. No part of this story may be used without permission.

LINK!

Thats actually pretty funny...

 

[FordPrefect]

My Star settings in the orbiter launch pad / parameters tab are:

Stars Count: 3000
Brightness: 0.02
Contrast: 5.00

...with this, I can barely spot the stars when I have the bright lunar surface or earth in view when in low orbit.
The star parameters in the next orbiter version are more advanced, though not directly addressing the described problem. As tblaxland said, it's the low dynamic range of the monitor.

On another note, the crew of Apollo 16 photographed Venus, incidentally, in one of their shots during EVA.

 

[Sherrif of Nottingham]

If I went out and got one of those wonderful Widescreen HD Monitors would there be a way?

 

[YL3GDY]

By the way, I recently had an opportunity to talk with Russian cosmonaut Kaleri. On a question about starry sky from space he answered that it's hard to see stars because of high contrast, too high for human eye.

That's because I set star count in Orbiter to zero. Also my monitor has a very small contrast(lower than 10000:1), so these stars look unrealistically bright.

 

[tblaxland]

If I went out and got one of those wonderful Widescreen HD Monitors would there be a way?

Plasma would give a better result to due their better contrast though these still have a relatively narrow dynamic range. To do better, you need to get one of these:
http://www.bit-tech.net/hardware/2005/10/04/brightside_hdr_edr/5

In particular, look at the table and compare the max/min luminance. Very impressive, but with an equally impressive price tag.

To get the full benefits you will also need a high dynamic range source, which will not be Orbiter for the time being.

 

[TSPenguin]

HDR displays are very nice, but you need a whole new infrastructure for them. Current display adapters can't even handle HDR data. So all we have now is artificial HDR (unless I overviewed something). But it sure as hell would be nice to have games in HDR on that (even saving some calculations for getting HDR data compressed into the regular spectrum). I'd love to make some HDR pictures of a half night sky half landscape and put them on that baby :speakcool:

 

[tblaxland]

Current display adapters can't even handle HDR data. So all we have now is artificial HDR (unless I overviewed something.

My understanding is that they can handle HDR data if they support DirectX Shader Model 3 or 4. As you say, the end result is artificial since the HDR source is compressed using tone mapping and/or light blooming for display on your regular monitor.

 

[TSPenguin]

My understanding is that they can handle HDR data if they support DirectX Shader Model 3 or 4. As you say, the end result is artificial since the HDR source is compressed using tone mapping and/or light blooming for display on your regular monitor.

I meant display adapters literaly. Sorry for the confusion caused.
The output to the display can only handle what normal screens display, nothing more.