• Question: Why do we need gravity???

    Asked by issi2001 to Anil, Blanka, Cees, Emma, Mike on 28 Jun 2012. This question was also asked by persionsupreme.
    • Photo: Blanka Sengerova

      Blanka Sengerova answered on 28 Jun 2012:


      For us on earth the really visible reason is that it keeps us sticking on the ground and not floating off into the air. Have you seen pictures of astronauts in the space station who just float about, as do all their things? Other that that, satellites revolve around the earth because of a gravitational pull. Do any of the other scientists know whether the atmosphere is somehow held towards the earth by a gravitational pull or am I just making that up now?

      But more seriously, the force of gravity which occurs between all bodies (planets, starts, asteroids) in the universe (the strength of it depending on the distance between the objects and their size) is what keeps the universe in its present state. The earth (and other planets of the solar system) revolves round the sun, the moon revolves round the earth and all of these bits of motion are dependent on gravitational force. As has been answered elsewhere, the reason for the orbits being circular (or elliptical) and the reason for planets being round is all to do with gravitational pull between celestial (in space) bodies.

      Is that good for a start? I’m interested to hear the things that the other scientists will be adding to this question…

    • Photo: Emma Trantham

      Emma Trantham answered on 28 Jun 2012:


      Yup the main reason I am very grateful for gravity is that it stops me falling off the Earth!

      Seriously though, I don’t think the planets would have really formed without gravity. Every bit of matter has some gravitational force around it (even us, although because we are so small that force is tiny). After the Big Bang when there were lots of bits of matter floating around in space, each with their own gravity field, the big bits of matter started to pull the smaller bits towards them. Eventually these clusters of matter got tighter and tighter until they were pulled together so much they formed planets. Or at least that is my understanding of what happened.

      Perhaps the others will have a better answer…

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