02 February, 1998. An Earth-orbiting satellite called Hipparcos
has spent the past several years observing the positions of stars
in order to measure parallaxes and proper motions. New data have
been released for several hundred thousand stars that give
parallaxes out to distances of 200 parsecs or more. Some stars and
clusters such as the Pleiades appear to be up to 10% closer than
believed; others are farther away. The results will alter our
views of the ages and of the structure and evolution of the stars.