Two meteor showers are on the horizon. The Delta Aquarids, visible between July 12 and Aug. 23, peak on July 28 at about 20 meteors an hour. The grand summer show of the Perseids, from July 17 to Aug. 24, peak on Aug. 12 with 50 to 70 an hour. The Aquarids will peak in a darker sky, while the . . .