The United States, Canada, Australia and Russia span several time zones. The most populous zones were used to represent these countries. Broadband use by country sourced from Wikipedia. If you don't see anything happening above, you may have better luck with a more HTML5-aware browser like recent versions of Google Chrome, Firefox, or Safari.
The circles above are sized according to the number of broadband subscribers in each country, as measured December 2009 - June 2011. China has around 117 million, the United States more than 83 million, and Romania at the bottom of this list has nearly 3 million subscribers. A single subscription may serve more than a single user. The day and night circles at the top are totals which change hour by hour depending on who's awake and who's asleep – obviously rendered in broad strokes. The further a circle is to the left, the more certain it is that most citizens in the country it represents are awake. The opposite is true for the right/night side. If you're wondering when to tweet your most brilliant thoughts in order to maximize International exposure, it looks like 9am EST or thereabouts is a pretty good bet! Of course, this doesn't take into account how likely it is that everyone is tuned into the Internet at that time.
If you like this visualization, you may also enjoy Stanley Cup Summed Up, The Weather Wheel, and The Dow Piano. Follow Bård Edlund on Twitter and Like EDLUNDART on Facebook for updates on various artistic projects.