William Blake’s poem Auguries of Innocence opens with these famous lines:

To see a world in a grain of sand,

And a heaven in a wild flower,

Hold infinity in the palm of your hand,

And eternity in an hour.

This poem came to mind when I saw @mathematicsprof post the following on Twitter:

At your next holiday party, look straight down into your glass of wine and tilt the glass one degree. You will see the elliptic orbit of the earth. If you tilt your glass 12 degrees you’ll see the orbit of Mercury. In general, if you tilt your glass θ degrees you’ll see an ellipse with eccentricity sin(θ).

(I’ve taken the liberty of editing the original tweets to take advantage of the extra breathing room outside of Twitter. Original tweets here and here.)

I like this for two reasons: it’s a great astronomy illustration, and it’s an example of how much information you can get into two 140-character messages.