On certain days during Boston’s long winter, residents can glimpse the stars by looking down. On the dove-colored surfaces of frozen ponds or lakes, shapes appear, rounded in the center with spiky arms stretching outward. The water, a scramble of gray and white, seems to mirror a star-pricked sky. Instead of appearing brighter than their surroundings, as their spacefaring counterparts do, these shapes are darker, showcasing the deep blue below. The moody wells and meandering branches might evoke a tie-dyed shirt or a squashed spider, legs akimbo. (Or, if your…