Summer solstice, a time when the northern hemisphere will experience the maximum hours of sunlight, takes place on June 21 -- and will be celebrated by followers of Wicca, a form of contemporary Paganism, with a holiday known as Litha. On this day the North Pole is at its greatest tilt toward the sun, creating the longest day and the official beginning of summer. As a sociologist of religion whose research has focused on contemporary Paganism, I know that for Wiccans, it is a day of celebration and joy at the light's full return.