Led by Julia Butterfly Hill, a group of activists and musicians are travelling the country in a bus fueled by vegetable oil, discussing wide-ranging issues such as peace, human rights, and the joys of being vegan.

The We the Planet Tour is the brainchild of Hill and her Circle of Life Foundation, which she founded after climbing down from a northern California redwood tree she had protected for more than two years. The tour started in San Francisco, where 10,000 people attended a kick-off festival featuring art installations, talks by celebrities, and performances by Joan Baez, De La Soul, Bonnie Raitt, the Coup, Tracy Chapman, and others. Soon after, the tour's biodiesel bus chugged out of San Francisco on its way to stops in a dozen cities across the country as various musicians, activists, and celebrities joined in for a few stops or more.

The bus recently stopped at the University of St. Thomas in St. Paul, Minnesota, where a packed house of 500 students and locals greeted Hill, Tracy Chapman, Howard Lyman, and two local activists -- 18-year-old gay organizer Vicki Pearce and Native American rights advocate Leah Tushay -- for a panel discussion and community conversation.

Once everyone onstage had spoken briefly about their own activism, Hill invited the audience to join the conversation. Students and local activists lined up at the microphones to discuss issues ranging from the military to biodiesel to re-usable menstrual pads. The unstructured format -- with the audience playing an essential part -- proved to be a major asset to the event. 'It's been amazing to see how different each night is,' Hill said later, 'because we really are bringing forward a space for the community to step into.'