Cancer, a constellation and the fourth sign of the zodiac. Cancer is the Latin name for crab; presumably, the unknown person who named it thought the constellation resembled that animal in shape. The Tropic of Cancer, an imaginary line 23 27' north of the Equator, marks the northernmost points reached by the sun's vertical rays. It is so named because in ancient times the sun was highest in the northern sky when it was in the same area of the sky as Cancer.
Although other planets have rings, none are as spectacular as Saturn's. What makes the planet's stratified rings, and how did they get there in the first place?
A ball of fire blazed through southern Peru and left a huge crater -- and then villagers started getting sick. Early reports said the groundwater boiled and the air filled with sulfur. What happened?