#1814: Color Pattern explain

[Cueball holds up his smartphone in front of his laptop which stands in front of him on a desk. Megan is sitting in an armchair reading, facing away from Cueball. She is singing her reply, as indicated with four double musical notes around her two lines of text.]

Cueball: I took a picture of my computer screen—why is the photo covered in these weird rainbow patterns?

Megan: When a grid’s misaligned with another behind

Megan: That’s a moiré…