• Question: If you had a balloon filled with helium and let it go, how high would it go before it started falling back down to earth?

    Asked by jamjarjarvis TGS to Connor, Jillian, Lidunka, Sarah, Steven on 15 Jun 2015.
    • Photo: Lidunka Vocadlo

      Lidunka Vocadlo answered on 15 Jun 2015:

      @jamjarjarvis TGS Well a helium balloon would rise into an atmosphere which gets less dense as you go up. So the pressure outside the balloon drops the higher it goes and the balloon expands until, depending on the strength of the balloon material, it eventually bursts. This probably will happen after a few 10s of km

    • Photo: Steven Thomson

      Steven Thomson answered on 15 Jun 2015:

      Good question! Special high altitude balloons filled with mixtures of helium and hydrogen can go as high as 120,000 feet – there’s even one that’s made it to 173,000 feet, which is almost 33 miles high! They can’t ever make it all the way into space, though, unfortunately.

      Regular helium balloons wouldn’t be able to go as high because they’re made of weaker material – the gas inside them expands as they get higher and regular balloons would quickly burst before they got anywhere near as high as that.

    • Photo: Jillian Scudder

      Jillian Scudder answered on 19 Jun 2015:

      High altitude weather balloons look like they make it 20 – 30 km into the air pretty regularly! Sometimes they then burst and fall back to earth, or they deflate over time and fall back down, with whatever devices they were launched with.

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