Posted in Web Summer solstice: The science behind the longest day of the … The summer solstice falls on June 20 or 21 every year in the Northern Hemisphere. Here’s why this day is the longest day of the year, with the most hours of daylight. Comments (0) On the summer… https://www.livescience.com/planet-earth/summer-solstice-the-science-behind-the-longest-day-of-the-year