The UW-Madison Arboretum offers 17 night walks a year, including one on each month close to the full moon, walks near the summer solstice and other changes of season, and one on New Year’s Eve, outreach and education manager Molly Fifield Murray said. On average, about 40 people attend each walk — accompanied by two naturalists funded by Friends of the Arboretum — though weather is a factor in attendance. The walks are free.