The discovery of minerals requiring liquid water for their formation challenges the paradigm of comets as “dirty snowballs” frozen in time.

Dust samples collected by high-flying aircraft in the upper atmosphere have yielded an unexpectedly rich trove of relicts from the ancient cosmos, report scientists from the Carnegie Institution.

The interstellar stuff that became incorporated into the planets and life on Earth has younger cosmic roots than theories predict, according to the University of Chicago postdoctoral scholar Philipp Heck and his international team of colleagues.

Scientists are puzzled by the composition of a mysterious space rock discovered in Antarctica.

By ALICIA CHANG SAN FRANCISCO - Detailed observations from the first comet samples returned to Earth are debunking some of science's long-held beliefs on how the icy, celestial bodies form.