Why is the sky dark at night?

[chris]

Well, I never.

[Glutton4...]

My brain hurts...

[piskieinboots]

Loving the 'baby stars' ... me too G4!

[arpoet]

It lost me after about 40 seconds....

[veggiechicken]

I thought it was dark because of all the clouds - never thought beyond that

[Mikey]

I tried really hard, but he was throwing too many new things at me, and my brain got a little confuddled around the chain plug border bit...so is the night dark because it is the left over water from VC's fathers bath?

[veggiechicken]

Well he's up there somewhere but I've always blamed him for the rain, not the dark skies

[Bren In Pots]

It lost me after about 40 seconds....

I cheated and switched of the sound then made up my own words

[Mikey]

I cheated and switched of the sound then made up my own words

So when they put the big camera on top of the Earth, did your commentary have something about big brother?

[taff]

how cool

[SlugLobber]

Now, I'm a scientist with 13 years post-grad experience and I thought he was going fast!

Still, from that I got:

1) In theory the sky looks blue in the day because of the sun's light scattering through the earth's atmosphere. Without atmosphere, the sky would be dark day or night.

2) If you looked in any direction with infinite vision, you would, in theory, see stars in all directions, meaning that the sky *shouldn't* be dark at any time! But...

3) Stars are moving away from us as the universe expands. The Doppler effect (don't ask) means that the further away the stars, the further into the infrared they become and so the more invisible. So...

4) We see the stars which are closest or are bigger. We don't see further away stars because they are in the infrared spectrum and so are invisible.

Do I get a prize????? Or a headache tablet?

ETA: I'm a Biologist, not a Physicist. Couldn't deal of those equation thingies. They're evil!!

[snohare]

Yeah, obvious, innit ? I knew all that...
Scarily, I did. I do need to get out more, don't I ?
In defence, can I just say that normally when I see this sort of article (or anything mentioning the word "quantum", which is total brainsprain) in New Scientist, I turn the pages until I come to something easier !
So really, Lobber's points 3 and 4 are the story in a nutshell, he could have talked at half that speed...
Now, can someone tell me how two particles that have never actually existed, can become quantumly entangled so that each knows instantaneously what the other one is doing...'cos supposedly some clever bod has done it.

[Florence Fennel]

The Doppler effect (don't ask) means that the further away the stars, the further into the infrared they become and so the more invisible.

Well I never, and there's me thinking it's the outfit Sheldon likes to wear at Fancy Dress parties

[cardiffsteve]

Ye canna change the laws of physics.

So if stars are flying away from us are supposed to be red shifted, why do they look silver?

[Capsid]

Ye canna change the laws of physics.

So if stars are flying away from us are supposed to be red shifted, why do they look silver?

The stars we can see are in our own galaxy, the Milky Way, and not moving away from us.