Craig Swanson of Reisterstown noticed Baltimore's sunrise and sunset were not 12 hours apart on the March 20 equinox: "Is this because we are north of the equator?" Nope. Day and night were equal that day everywhere - if you marked sunrise and sunset when the center of the sun's disc touched the horizon. But we calculate sunrise and set times using the first (and last) light from the sun's rim, making "days" a few minutes longer. They are 12 hours apart here March 16 and Sept. 25.