I love the song, and I love the big full moon.
There is a lot of detail at the site, but here's the summary:With these being the very last few days of summer, the full moon that graces our skies tonight becomes the Harvest Moon. So named because it helped farmers to bring in their crops on time, it also marks a special time for sky watchers and gives a great opportunity to see an amazing optical illusion that makes the moon look exceptionally big.
...[T]he curious optical illusion known as the 'Moon Illusion' will likely be especially noticeable to anyone watching the moon as it rises tonight or sets in the morning, making the moon look huge when it's near the horizon.And here's a version I remember (please let me know if it doesn't show up):