Dear Everyone.

 

I expect I'll be back but basically this is the question I've joined to ask.

 

I've seen loads of NASA pics. of The Earth from Space - but you'd expect to see loadsa stars in the background, many more than you usually see on light-polluted Earth (on the whole!) But there's never any, Space is always jet black in NASA shots without a star in sight.

 

Evidence: http://earthobservatory.nasa.gov/blogs/elegantfigures/2013/04/22/earth-day-and-night/comment-page-1/

 

Like - where's the rest of the universe gone!?! (Google 'NASA Pictures of Earth from Space' and you'll find every one is galaxy-free! And the same with the Moon, Jupiter even.)

 

I'm sorry in advance if this is a Really Dumb Question to you experts, but I've never found a definitive answer to it.

 

Yours in extreme puzzlement

 

Chris.

No, it isn't an uncommon question. Has to do with the level of illumination and the typical camera settings used.

 

https://en.wikipedia.org/wiki/Examination_of_Apollo_Moon_photographs#Absence_of_stars

Short answer is if you could see the stars, the earth would be massively overexposed in the picture.

And, just like on Earth, you can see stars if the picture is taken at night: http://earthobservatory.nasa.gov/IOTD/view.php?id=88026

Another way to put it: because the light intensity range from darkest to lightest is too wide for a camera to record faithfully in circumstances like that, you have to choose which element you want properly exposed and leave the others pure black or pure white with no detail, hence, the featureless, black sky because the Earth was the desired feature in those pictures to be recorded properly.

Edited September 29, 20169 yr by StringJunky

Dear Everyone.

 

Thankyou very much for all your answers, all of which have helped me understand the phenomenon!

 

To 'Strange' er-pardon the ignorance again - isn't it ALWAYS night in Space, or were you having a joke and I missed it?

 

Yours with thanks

 

Chris

Dear Everyone.

 

Thankyou very much for all your answers, all of which have helped me understand the phenomenon!

 

To 'Strange' er-pardon the ignorance again - isn't it ALWAYS night in Space, or were you having a joke and I missed it?

 

Yours with thanks

 

Chris

If you are in direct sight of the sun it is daytime. You need to be on the dark side of whatever body you ate standing on - in shadow - for it to be night. The sky will be dark, with stars visible, if you are out floating in free space but you and any objects around you will be lit up.

 

Edit: I suppose one could argue there needs to be a dense enough atmosphere to scatter sunlight to create the daytime conditions we experience on Earth and, therefore, it's always night without one.

Edited October 2, 20169 yr by StringJunky