how did we know that there is no air in outer space before we sent a spaceship up there?

Answer 1

1. It has been known for a long time that atmospheric pressure decreases as you go up in elevation. By extrapolating that pressue versus altitude curve, it becomes clear than the atmosphere becomes vanishingly thin within 100 miles of the surface.

2. The atmosphere is made up of molecules of various gases. Those molecules have mass. The mass of the atmosphere is held to the earth by gravity. The force of gravity decreases as you get further from the earth's center. Therefor the force holding the atmosphere decreases as you go up, and the gases get thinner, until you reach a point where the brownian motion of the molecules is stronger than the force of gravity, and the gas escapes.

3. Observing meteors, it is noted that they come out of "nowhere" and become increasingly bright as they fall to earth. That brightness is due to heat from friction with the molecules in the air. Extrapolating backwards, from bright to dim to invisible, you can deduce that there are too few molecules in space to cause enough friction for the meteor to be visible.

Answer 2

The fact is that we didn't know it, at least not for sure. Before we actually got up there, the most we could do is come up with theories about it, and hope that our theories weren't disproven by other scientists.

But, the first theories about the airlessneess of space began as scientists began to notice that there is a significant change in air pressure the higher in altitude we go, that places where the earthe is below sea level have higher air pressures than places that are at sea level, which is higher than any points on up the sides of any mountains.

So, the theory started out that at some point, air pressure would reach 0.00 psi, (pounds per square inch, which also happens to be the exact same measurment in kilograms per square meter, but, the metric system didn't actually exist way back then...) and that would be the definition of an airless total vacuum of space.

The fact, however, is that there are measurable quantities of free-floating molecules of hydrogen and helium and nitrogen in outer space, so even though the pressure would be measurable in terms of micrograms per square terameter, there IS air in space, just not enough for most forms of life as we know it to survive in.

Answer 3

Things like meteoroids (and sometimes, shuttles) burn up on entering the Earth's atmosphere. That is because basically all objects in the Solar System are moving at many times the speed of a rifle bullet and the friction on encountering even the thin air high in the atmosphere is enough to heat objects at those speeds up to thousands of degrees.

If space was full of air, all the trillions and trillions of meteoric particles would be burning up all the time.

In fact as others noted above, everything would be subject to that friction and the regular clockwork motions of all the Solar System objects would wind down in a very short time.

There are some things that are obvious from simply thinking logically.

Answer 4

Although scientists would have known space was airless long ago, it's interesting to see that ordinary people probably weren't aware of it. Georges Méliès' famous 1902 film, 'Le Voyage dans la Lune', which probably introduced many people to the idea of space travel, appears to ignore the issue completely.

In that film, when the brave 'astronomers' land on the moon - well, who else would take such a trip? - air and gravity are both normal. Presumably the audience was left unaware that extraterrestrial conditions are anything unusual.

Well, it's a fantasy - a little like Terry Gilliam's moon in 'Munchausen'. Nowadays, though, only young children would be taken in.

CD

Answer 5

"We" haven't ever sent any ships into 'outer space'. And 'we' most certainly never will. The size of just our own solar system is incomprehensible. Just like 'The Times', or for that matter, 'The Sun' are, to your dog! But the solar system is 'just' something that is within our 'galaxy' (we've all agreed to call our galaxy "The Milky Way").

'Outer space' is not merely outside our solar system, it is outside our galaxy!!!

The next-nearest galaxy to our Milky Way is "Andromeda" (with which, in a few billion (!) years, our own 'Milky Way' will merge). THAT is "outer" space.

As for the air. Well, quite simply: If there was any air, then it wouldn't be "space". It would be air: Molecules! Atmosphere!

Such things always congregate (gravity) around big, massive objects such as stars and planets because of gravitational force - which all of us can understand. Thus, beyond these areas: no molecules. And that includes 'no' "air" molecules too!! Simple!

Answer 6

Logically it would make sense. The higher we get up a mountain, the less air pressure there is. It would make sense that at some height, the atmosphere would thin off into virtually nothing. When we look into space, if space were filled with air, the light from stars, and even the sun, would get refracted off into many random directions meaning we wouldn't be able to see jack diddeley in the night sky.

Answer 7

Good question. Simple answer...

Because when you go up in altitude above the surface of the Earth, the higher you go the the less air pressure there is. If you follow that reasoning, if you went high enough there would be zero air pressure which means that there is no air, or such a tiny amount that it is not measureable. Indeed, that is exactly what early high altitude pilots discovered when they went to very high altitudes in jet and rocket powered aircraft.

Answer 8

Newton's 0.33 regulation of action: III. for each action there is an equivalent and opposite reaction. think of protecting a heavy weight and status on a skateboard. Now, throw the load removed from you. the load will pass forwards, and the skateboard will roll backwards. attempt it! the reason the skateboard rolls backwards is that, in consequence, you have pushed against the load. precisely 0.5 of the flexibility in that push has propelled the load removed from you, and the different 0.5 has been used to propel you removed from the load. If the device is now replaced so as that the load is replaced by making use of a constantly working rocket motor, 0.5 of the flexibility would be used to propel burnt gasoline (increasing gases) out of the motor, and 0.5 would be used propelling the motor removed from the increasing gases. In a device without losses using friction or air resistance burning will reason acceleration and no burning will reason the fee to be maintained.

Answer 9

I love these questions. There the kind of question a 3yo child asks. Air has mass and gravity exerts a force on mass. Therefore gravity holds all of the earths atmosphere tightly round the planet. As you get further away from the planet you get further away from the mass of air. You eventually leave the atmosphere which is held close to the planet behind.
Theres a lot more to it than this simple answer but I have to remember I'm answering a 3yo

Answer 10

Asronomical observation. For thousands of years mankind has managed a healthy understanding of the movements of comets. They retain a static momentum, which means they don't slow down. Any presence of air would create friction and they would slow down.