Whirlwind, a general term for any whirling body of air. The term is most often applied to whirling air created by the swift rising of warm air from near the surface of the earth. Whirlwinds include the "dust devils" that may be seen moving across a field or along a dirt road on a hot day, and the waterspouts of tropical seas.
Folks in Montana usually expect snow or rain to fall from the sky, not ash. But the 1980 eruption of Mount St. Helens in Washington flung ash across state lines. What is this gritty, gray stuff?
Scientists announced the discovery of the largest known planet in the universe. TrES-4 has a density similar to balsa wood, and some say this gas giant could float on water. Learn why this planet is so puzzling and how planet hunters make amazing discoveries like these.