Cosmic Expansion and Ho: A Retro- and Pro-Spective Note

Abstract

Attempts to measure extragalactic distances over the last 90 years are briefly described. It follows a short history of the discovery of the expansion of space. Reasons are discussed for the decrease of the Hubble constant from Ho~500 originally to Ho<~60 at present. Remaining problems with Cepheids as local distance calibrators are outlined.

15 pages (2 figures). To appear in the proceedings of the XXXVIIth Moriond Astrophysics Meeting "The Cosmological Model", Les Arcs, France, March 16-23, 2002. Revised version with minor changes and additional references