... Like cosmic snowballs, fluffy comet-like objects the size of houses and composed mostly of water-ice, may be pummeling planet Earth 5 to 30 times a minute. ... Southern Neptune . ... Neptune, the Solar System's outermost gas giant planet, is 30 times farther from the Sun than Earth. ... Like a distant mirror of Earth dwellers' hopes and fears for the future, Mars, the fourth planet from the sun, has inspired profound works of fiction as well. ... Saturn's Rings Seen Sideways . ... The Heart Of Orion...