An accurate distance to the nearest galaxy

摘要

Distances to celestial bodies are crucial in astronomy. They allow astronomers to understand the structure of the Universe; for example, to see the organization of the Solar System and to recognize that galaxies lie beyond the Milky Way. The derived physical sizes of bodies scale with the distances adopted for them, whereas their energetics scale with the square of the distances. A current hot enterprise is to use distance measurements to the farthest supernovae to map out the expansion history of the Universe and to uncover the nature of the Universe's mysterious dark energy. Distances are deduced by means of a 'distance ladder': knowledge of the distances to nearby bodies is used to determine the distances of bodies farther out, and so on to yet more remote objects. On page 76 of this issue, Pietrzyriski et aV claim to provide a much-needed, highly accurate measure of the distance to the Large Magellanic Cloud galaxy - the bottleneck in the ascent of the distance ladder.