Link to column: Why does the moon appear bigger near the horizon?
Cecil got this one wrong – he says that the Moon appears bigger on the horizon because of visual cues of surrounding objects. Trees, houses, etc. appear small so the Moon appears large by comparison. He then says that even waves at sea appear smaller. It’s clear that The Master has never spent much time at sea. Phil Plait, aka The Bad Astronomer, aka former Doper BA debunks this explanation as well. Out at sea (where wave sizes cannot be accurately judged) or in the desert (are we comparing the Moon to grains of sand?) the illusion still holds.
As further proof of this, try looking at the Moon upside down, through your legs. Even with visual cues such as houses and trees, the Moon appears normal size. In fact, no one is quite sure why the illusion occurs, but the best explanation so far is that the sky itself is the visual cue. Since the sky appears as a flattened bowl (Cecil got this part right), the sky appears farther away at the horizon, giving the illusion that the Moon is bigger by comparison.