• Question: what would happen if we had two moons?

    Asked by Wurly135 to Daniel, Hannah, Maggie, Ry, Scott on 6 Nov 2017.
    • Photo: Scott Melville

      Scott Melville answered on 6 Nov 2017:


      The sea would get really weird.
      The Moon pulls the ocean around as it goes around the Earth, which is why there’s a tide at the beach. If we had two moons, the water at the beach wouldn’t just get high and low once each day, but do something much more complicated!

    • Photo: Maggie Lieu

      Maggie Lieu answered on 6 Nov 2017:


      If we had 2 moons, then their gravity will affect our tides. Maybe there would be larger waves on some parts of the world and shallower seas at times on the other side of the world. It also affects the Earths spin, so if it slows down then we would have longer days and nights. But overall I think it would be pretty cool to look at. Mars has 2 moons, phobos and deimos. It means more places in our solar system to explore 🙂

    • Photo: Ry Cutter

      Ry Cutter answered on 6 Nov 2017:


      If we imagine it’s an almost complete clone of the moon we currently have (same distance, same size), the second moon would have some pretty neat effects on Earth. There’s a chance we’d see two moons in the sky, that would be cool. The problem is, will these moons interact. If the second moon is in an unstable position, there’s a chance the two moons could crash into each other (I’d like to see that personally).
      More to the effects on Earth, the tides would definitely be thrown out of whack. There’s something called a chaotic pendulum (double pendulum), the tides will have a very similar relation to this motion with two moons. So many animals would get confused as well, some animals use the moon as a clock. A lot of animals use the moon to navigate, with two moons they’re going to get lost!
      We’d have double the eclipses though, and they’re very pretty!

      Great question,

      Ryan

    • Photo: Hannah Middleton

      Hannah Middleton answered on 6 Nov 2017:


      If we had two moons, we would have much more complicated and variable tides. With one moon, we have two high tides every day. But with two moons, we might get different numbers of high tides depending on the positions of the two moons. If both moons happened to be on the same side of the Earth, it could cause a much higher tide.

      The moon also affects the rotation of the Earth, so if we had another moon then the length of our days might change.

      Our system of measuring dates would be different too! Some calenders are based on the phases of the moon, so that would all change if we had two.

    • Photo: Daniel Williams

      Daniel Williams answered on 7 Nov 2017:


      It depends on how big the second moon is! In some respects the earth already has thousands of moons – the satellites which orbit it to help us make weather forecasts, and to send information, like TV broadcasts and the internet, around the world. The very first satellite was Sputnik, which was a launched by the USSR (a country which was made up of countries like Russia and Ukraine) on 4 October 1957, so in a sense it was our first “second moon”.

      Now, if we had a second moon the same size as our moon I think you’d get lots of problems with weird tides like the other scientists have said, and it might have made the moon landings twice as expensive if we’d needed to land on both of them.

      It might also mean that our month was a different length, because it’s based off how long it takes the moon to go from one full moon to the next. Who knows what we’d have come up with if there were two moons.

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