Nearly 4 years ago, two teams of observational astronomers reported that hi
gh-redshift Type Ia supernovae are fainter than expected in a decelerating
or freely coasting universe. The radical conclusion that the universe has b
een accelerating in the past few billion years, possibly because of a nonze
ro value for Einstein's cosmological constant, has gripped the worlds of as
tronomy and physics, causing a flurry of new research. Having participated
on both teams (but much more closely with one than the other), here I provi
de a personal, historical account of the story.