• Question: will the moon ever lose gravitational pull and make the moon collide into us?

    Asked by yehscience123 to Simon, Julia, Delma, Andrew, Alex on 13 Dec 2015.
    • Photo: Andrew Winnard

      Andrew Winnard answered on 13 Dec 2015:

      Hi Yeahscience!

      This a good gravity lunar question! Luckily, I dont think we need to build any moon crash bunkers to hide in for when the moon crashes into us. Its much more likely that the moon will actually fly away and leave Earth behind on day!

      It is thought that the Moon was formed when a proto-planet about the size of Mars collided with the early Earth around 4.5bn years ago. The debris left over from impact coalesced to form the Moon. Computer simulations of such an impact are consistent with the Earth Moon system we see in the 21st Century.

      The simulations also imply that at the time of its formation, the Moon sat much closer to the Earth – a mere 22,500km (14,000 miles) away, compared with the quarter of a million miles (402,336 km) between the Earth and the Moon today.

      The Moon continues to spin away from the Earth, at the rate of 3.78cm (1.48in) per year, at about the same speed at which our fingernails grow. So this is REALLY slow! Without the Moon, the Earth could slow down enough to become unstable, but this would take billions of years and it may never happen at all.

      Did you also know that the same side of the Moon is always facing us too? So whenever you look up into the ngiht sky and see the moon you are always looking at the same part of it!

      Here is a video for you that explains this:

      PS: The astro support team will start getting evicted this week from Tuesday! If you like my replies where I try to include videos for you then please vote for me – and check out the videos I made myself specially for you guys this weekend on my profile page! 😀

    • Photo: Delma Childers

      Delma Childers answered on 14 Dec 2015:

      Most likely, no. In fact, as Andrew said, the moon is actually slowly drifting away from the Earth (at about 4 centimeters a year).

      But some people have had the same idea you’re asking about and put together a clever, but not entirely accurate, little simulation:

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