Perseid meteor shower over Tenerife, Spain © Westend61/Getty Images

Not every summer tradition happens on the ground. Some unfold hundreds of miles overhead, one meteor at a time. The Perseids return each year from mid-July through late August, peaking around 12-13 August, when as many as 100 meteors an hour can streak across dark skies. Each meteor is a tiny fragment left behind by Comet Swift–Tuttle as Earth passes through its dust trail, appearing to radiate from the constellation Perseus. In Spain, the display is affectionately known as Lágrimas de San Lorenzo ("Tears of Saint Lawrence").