Most of the many souls clad in rainbow tie dyes, gauzy wings and magic felt hats at the 44th Annual Whole Earth Festival celebrated Mother's Day on May 12, according to the Gregorian calendar.
But about a dozen star travelers from across the universe camped out in a spherical geodesic dome where they observed "Red Spectral Moon Day."
They also called it "Magic Turtle Day.
Red Spectral Moon Day is part of the World 13 Moon - or 13-month - Calendar Change Peace Movement advocated by Davis Whole Earth Festival founder José Argüelles, a UC Davis art history professor who died in 2011 at age 72.
Argüelles claimed that the 12-month Gregorian calendar dating back to Roman Emperor Julius Caesar - with months jumping from 28 to 31 days - is irregular, artificially regulates human affairs and is out of synch with the natural order of things, promoting disharmony and conflict.
"It's followed in 90 different countries, including China and Brazil, and it's strongest in Latin America," home of the Mayan calendar, explained Jacob Wyatt of the non-profit Foundation For the Law of Time in Ashland, Ore.
Venezuelan Kelly Harding said she learned about the 13 Moon Calendar in her village. "I always thought something was off with the Gregorian calendar, and this really rang true. It's a grass-roots movement - we can't depend on institutions or the government to change it."
The League of Nations and United Nations both considered adopting a 13-month World Calendar, but the United States and the Vatican blocked it, said Jesse Bossert, also of the Ashland nonprofit.
Argüelles, who launched the Davis Whole Earth Festival in 1970, also helped organize the 1987 Harmonic Convergence held at sacred sites around the world. His slogan, "Time Is Art," was the theme of this year's festival.
Mahatma Gandhi in 1931 favored a standardized 13-month calendar - with each month 28 days - if it would unify the planet, said Tim Tussing, a math professor at Ohio State University. A 13-month calendar has been used at various points over the past 6,000 years by Chinese, Hindus, Egyptians, Polynesians, Druids, Maya, Inca, Lakota Sioux and Cherokee, Tussing said.
The extra 365th day, or Day Out of Time, is an official holiday in Sao Paulo, Brazil, the world's second largest city, Tussing said.
Call The Bee's Stephen Magagnini, (916) 321-1072. Follow him on Twitter @stevemagagnini.