The eye-catching delta and green swamps of the Paraná River (image left) on the Atlantic coast of Argentina... The Paraná River, South America’s second largest after the Amazon River, pours brown muddy water into a wide estuary known as the River Plate (image center and right). The gray mass of Argentina’s capital city, Buenos Aires (metro population 12.74 million in 2010), is less prominent seen from space (down right), although astronauts quickly attune their eyes to the subtle signature of such cityscapes....