SA Special Editions

Like a boiling teakettle atop a COLD stove, the sun's HOT outer layers sit on the relatively cool surface. And now astronomers are figuring out why

Although one of Earth's nearest neighbors, this strange world remains, for the most part, unknown

Venus's climate, like Earth's, has varied overtime--the result of newly appreciated connections between geologic activity and atmospheric change

Evidence is mounting that other planets hosted oceans at one time, but ONLY EARTH has maintained its watery endowment

The Red Planet is no dead planet

Asteroids have become notorious as celestial menaces but are best appreciated in a positive light, as surreal worlds bearing testimony to the origin of the planets

GALILEO SPACECRAFT, beset by technical troubles, still conducted a comprehensive study of the JOVIAN SYSTEM. Few predicted that the innards of these worlds would prove so varied

Doodles and freckles, creamy plains and crypto-icebergs--the amazing surface of Jupiter's brightest icy moon hints at a global sea underneath

What an impoverished universe it would be if Saturn and the other giant planets lacked rings. Planetary scientists are finally working out how gravity has sculpted these elegant ornaments

On the outskirts of the solar system swarms a vast cloud of comets, influenced almost as much by other stars as by our sun. The dynamics of this cloud may help explain such matters as mass extinctions on Earth