| 18 June 2010

Photo: slezo Have you noticed yourself smiling a bit more than usual today? Is there an extra spring to your step and a twinkle in your eye? If so, it might be because today, June 18, is the happiest day of the year--at least that's according to a special mathematical formula designed to measure happiness. Developed by a psychologist, the formula considers several green "feel-good factors" to determine the year's most cheery date, such as the season, likel... Read the full story on TreeHugger