The lunar phases describe the form we perceive the moon having based on the light it reflects from the sun while being partially turned away from us.

Q: Can we abuse science to make the moon have physical phases?

By having physical phases I mean that the physical shape of the moon changes in cyclic manner. Thus if one would land on the moon, in its crescent the moon would be an actual crescent opposed to just appearing as one due to what we see reflected.

We can do the following things:

We can not do these things though:

  • change the mass of the moon
  • 4
    $\begingroup$ The phases of the moon have nothing to do with it "being partially hidden behind our own planet." They're caused by the side of it that's illuminated by the sun being partly turned away from us. $\endgroup$ Sep 26, 2016 at 6:01
  • 4
    $\begingroup$ What do you mean by physical phases, exactly? $\endgroup$
    – Mołot
    Sep 26, 2016 at 6:05
  • $\begingroup$ Yeps, I totally messed up that part of the question. Comes from writing something up before class $\endgroup$
    – dot_Sp0T
    Sep 26, 2016 at 9:13
  • $\begingroup$ What do you expect the Moon to be in a new moon phase? $\endgroup$
    – user8808
    Sep 26, 2016 at 13:13
  • $\begingroup$ @Roux a ring similar to this solar eclipse $\endgroup$
    – dot_Sp0T
    Sep 26, 2016 at 13:32

3 Answers 3


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Changing your moon's shape

Make it look a bit like a really fat crescent roll. And slightly more crescent like as well. This would mean that the center part should give a circle shaped view while if you saw it from the side, it would look like a crescent. Now just have it rotate as per normal and voila.

So it's not exactly having your moon change into a crescent and then back into a sphere. But it might be the most feasible one. And then you can hand wave the fact that someone took a real large bite out of your moon.

  • 2
    $\begingroup$ And you'd also need to change the composition of the moon - exceeding the potato radius will pull it right back to being a sphere again unless you do something about. $\endgroup$
    – user10945
    Sep 26, 2016 at 14:42
  • $\begingroup$ @Pete as Carl Sagan would say: "We've got space-magic for that, boy" $\endgroup$
    – dot_Sp0T
    Sep 26, 2016 at 14:51

There's only two things you can do:

Change the Moon's Orbit

For this, you need to find a way of accelerating or decelerating the moon's orbit, or changing it's distance from the earth. Obviously, these will have effects on the earth's tides, it's rotation, and possibly the earth's axis. It wouldn't be a nice experience.

Create a Space Parasol

You could also create a massive shade and use that to project a shadow onto the moon. This would also throw a shadow onto the earth at certain points in the cycle and could well turn out to be pretty confusing to it's inhabitants.

Changing the moon's composition or making it rotate differently won't do anything to change the phases.


You'd need to lunaform (lunar counterpart to terraform) continuously, so, possibly, since you can alter its composition, but not it's mass, perhaps remake it into completely out of nanomachines that shift to change the shape of the 'moon'?

  • $\begingroup$ i doubt you can get the necessary kind of strength in your nanomachine to withstand the gravitational pull of all that mass. Large masses tourn into spheroids for a reason. $\endgroup$
    – Burki
    Sep 26, 2016 at 15:06

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