the

Why Does The Sky Change From Blue To Black? | Secrets of Everything | Brit Lab | BBC

he is dr. Sevigny fidlow I just call him

doc

doc and I are on the way to meet Steve

Randall his weather balloons travel to

the edge of space so we're hitching a

ride to find out exactly why the sky

changes from blue to black we're gonna

send up a couple of these cameras in the

payload and then we're gonna analyze the

footage that comes back as well as

filming the color of the sky we'll be

taking other readings too this is a

thermometer and this bit measures

atmospheric pressure or in other words

how much air is left above our craft and

this is the crucial bit missed the GPS

we didn't have this it wouldn't be able

to find it again and that it's gonna be

our payload the beauty

I've always wanted to launch a spaceship

but I never thought it would look like

this although we've now lost visual with

spaceship one

it's just spots of 5,200 meters here at

Mission Control Steve's in constant

contact

at 10,000 meters spaceship one is over a

kilometer higher than Mount Everest and

when it gets to 20,000 meters higher

than any airliner flies the blueness of

what we see from the ground as sky is

now just a thin line on the Earth's

horizon

up here there's almost no atmosphere at

all the helium in the balloon expands as

it tries to fill the void of space

now that race is on to recover spaceship

ones reentry module we've got to go to

it's kind of last-known position roughly

and then try to track it locally success

okay let's get it open we need to have a

look at the footage doc and Steve now

analyzed spaceship ones data of mission

controls Research Center to find out why

the sky gets blacker the further you go

into space

straight away our video shows how the

color blue drains away the higher the

blue gets but what about the other

measurements what about temperature and

atmospheric pressure now if we have a

look at the precise color measurements

from those pictures what we find is that

the color changes a lot as you go higher

and higher and higher until you're a lot

higher and it doesn't change as fast

temperature also changes as you go

higher but it kind of changes at a

similar sort of rate until you get to

the top it doesn't change that much

it's our the air pressure the thickness

of the air also changes as you go up and

it does so they're very similar way

- the color and that's what it's all

about as the air gets thinner at blue

sky fades to black so the sky is blue

because of the thickness of the

atmosphere above us and the light

bouncing off all the air molecules and

dust particles take away their

atmosphere and the sky would be black

just like it is in space

you