d nearly all t tance of treat are neatlyproportional: ter it is moving.  tion, ant, v is ty of a flying galaxy, andd its distance a and ted t t tle ae 1920s it  many t least Eartself—. Refining tion of cosmology.

    Almost tant about tant  ofdisagreement over o give it. In 1956, astronomers discovered t Cep; ties, not one. to reions and come up o 20 billion years—not terribly precise, but at least old enoug last, to embrace tion of th.

    In t folloed a long-running dispute bet ilson, and Gérard de Vaucouleurs, a Frencronomer based atty of texas. Sandage, after years of careful calculations, arrived at a value for tant of 50, giving tain t tant was 100.

    2t t Sandage believed—ten billion years. Matters took a furto uncertainty ories in California,using measures from telescope, suggested t ttleas eigarseam from NASA and tCenter in Maryland, using a neellite called tropy Probe, announced  take a ters rest, at least fort.

    ty in making final determinations is t ten acres of room forinterpretation. Imagine standing in a field at nigrying to decide ant electric ligraigools of astronomy you can easilyenougermine t tness and t one is, say, 50 percent moredistant t  be certain of is  ussay, a 58-t bulb t is 122 feet at lig is 119 feet, 8 incop of t you must make alloortions caused by variations in tmospergalactic dust, contaminating ligars, and many otors. t is t your computations are necessarily based on a series of nestedassumptions, any of ion. taccess to teles