A Sundial that Shows Solstice . ... If the time and day are right, this sundial will tell you: SOLSTICE . Only then will the Sun be located just right for sunlight to stream through openings and spell out the term for the longest and shortest days of the year. ... On two other days of the year, watchers of this sundial might get to see it produce another word: EQUINOXE . Resource Guide: NASA Education and Public Outreach . ... U. Based on Astronomy Picture Of the Day ...