Kind: captions
Language: en
Have you wondered what it would be like
to be an astronaut floating around in
the space station?
But why are the astronauts floating?
I'm here at the Powerhouse Museum in
Sydney to find out if anyone knows the
answer. Why are they floating?
No gravity.
Zero gravity.
There's no gravity.
Gravity. The stuff that holds us to the
planet when we spin doesn't happen up
there.
Gravity holds you the answer in space.
There's nothing there. So, you just
float.
There's no gravity in space.
No gravity. There's very little.
But is there really no gravity in space?
After all, the moon orbits the Earth due
to gravitational attraction.
So, where would the space station fit in
this picture? [music]
Can you make me a roughly to scale model
of the Earth and the Moon? And then
we're going to position the space
station in there. So about like that.
Yeah. About there.
Close up. Maybe about there. That.
You ready to see the real distance?
What do you reckon?
[laughter]
Oh, okay.
It's actually about here. Maybe a little
further.
I think we were wrong.
Now, if the moon is here and the Earth
is there, whereabouts would you put the
space station? Somewhere around here.
Further here.
Midway.
About halfway.
Yeah.
Right about here. So that's maybe like a
quarter of the distance to the moon. Let
me show you the real distance. Are you
ready for the real distance?
The space station is right about there.
That close.
Oh, okay. That close. Wow. [laughter]
We're not good at this game.
We're not.
The space station is actually only about
400 km away. So if you're in Sydney,
it's a little further than the drive to
CRA. But does it make sense [music] that
the Earth exerts a big gravitational
force on you, but nothing on the
astronauts just a short distance away?
You reckon there'd be no gravity there?
There's not much. They float. We've seen
them.
Well, clearly there's not. They're
floating around.
I know they float. And the question is
why?
No idea.
I'm really confused.
Well, in truth, the force on the
astronauts is almost as much as the
force on you.
So then why are they floating while
you're stuck here? The answer is the
astronauts aren't floating, they're
falling.
[screaming]
And not only that, but the space station
they're in is falling as well.
So why doesn't the space station come
crashing into the Earth? Well, the
reason is the space station and
astronauts inside have this huge
sideways velocity of about 28,000 kmh.
So even though they're falling towards
the Earth, they're going so fast that as
they fall towards the Earth's surface,
it curves away from them.
If the Earth didn't put a gravitational
force on them, they would fly out into
space.
Sure. Yeah.
Right. So, it's due to that
gravitational pull that they can
actually keep orbiting the Earth.
If it was to stop moving, it would be
plummeting. Exactly.
But would they
They would still feel weightless until
you smash into something.
So, the space station and the astronauts
inside are constantly accelerating
towards the Earth's core, but they never
get any closer. And because they're
accelerating at the same rate, the
astronauts feel weightless. They have
this amazing sensation of floating.