What is photoperiodisom?

Why are solar eclipse glasses necessary for viewing a solar eclipse safely? Why is gravity strongest at Earth's surface? Who invented the sojurnour? What explains the difference in wind direction between the surace and the upper atmosphere in the tropial paific near Hawaii? What aircraft did the first monkeys in space go in? What are the main reasons for putting shutters on windows? Why is the harvest moon so big and bright? How long is day and how long is night on earth? Why did Zeus hang Hera? Where does Ender Wiggin get his nickname? How long would it take for the world to fully turn around? How many space shuttles orbiters were there? How much mass is in outerspace? What are the 3 celestial bodies that have been redefined by the IAU as dwarf planets? Who the first humans to go to the moon? How a hot air balloon goes up and down? What is the typical size of the typical white dwarf in solar radii? Would water float on the moon? Why are difrent planets difrent temperatures? Does moon sand come from the real moon that is in space?