• Question: Hello (: My question is: why is there no atmosphere in space?

    Asked by nsweeney774 to Amy, Drew, Julia, Kimberley, Sara on 13 Jun 2011. This question was also asked by annelouise372, mizzerie150.
    • Photo: Drew Rae

      Drew Rae answered on 9 Jun 2011:

      Hi. Funny thing is, there are lots of gas particles in space, it’s just really really thin in most parts. Gravity makes things clump together as solar systems, or free planets, or clouds of gas. When things clump together, that doesn’t leave stuff over to fill the gaps.

    • Photo: Sara Imari Walker

      Sara Imari Walker answered on 10 Jun 2011:

      Hi nsweeney774! Drew has got it right! The reason we have an atmosphere is because the particles in the gas of our atmosphere are gravitationally attracted to the Earth. The heavier they are the more attracted they are. This is why dense fog tends to stick to the Earth (and make for nasty driving conditions!). If you’ve ever been through a dense cloud of fog you know it is heavy with water. Clouds in the sky have much less water and so they stay way above our heads. Even lighter gases can escape our planets atmosphere once they are far enough away from the surface of Earth. So, our atmosphere doesn’t stretch way out into space. Other planets like Jupiter, which are much much more massive than the Earth, have even bigger atmospheres! In empty space, away from planets, there is nothing to hold the gas particles together and so there is no atmosphere. Drew has pointed out that clouds can form in space though – if there are enough gas particles they can come together by their attraction to one another and make massive clouds which can be much bigger than even our entire solar system!

    • Photo: Kimberley Bryon

      Kimberley Bryon answered on 10 Jun 2011:

      I think that Drew and Sara have answered this really well. The reason that there is no atmosphere in space is because even though there are lots of gas particles there are so few of them that they don’t produce a measurable force. This is because:

      Pressure = density (how close together things are) of molecules x kinetic (movement) energy

      Space is so big that the gas molecules that are there don’t collide very often so don’t produce much pressure.

      On Earth the molecules collide a lot more often to give us our atmosphere.

    • Photo: Amy MacQueen

      Amy MacQueen answered on 11 Jun 2011:

      I think these guys all covered this – what’s also interesting is where does our atmosphere stop and “space” begin? In reality its a gradual thing but a few people, like NASA, have decided to name lines that define the boundary.

      🙂

    • Photo: Julia Griffen

      Julia Griffen answered on 13 Jun 2011:

      Very few things in a very very big empty space.

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