The 'Big Moon' Illusion May Be All in Your Head

If you've ever seen the moon as it's just coming over the horizon, you may have wondered why it seems to look bigger than when it lies straight overhead. Later, Hermann von Helmholtz (1821-1894), a German physicist known for his mathematics of the eye, theories of vision and ideas on the visual perception of space, asserted more or less the same idea: that when the moon is seen directly above the horizon, our brains unconsciously assign to it a dimension comparable to nearby