THE Universe may be smaller and younger than we thought. Astronomer Jim
Herrnstein of the Harvard-Smithsonian Center for Astrophysics in Cambridge,
Massachusetts, and his colleagues used the Very Large Baseline Array of
radiotelescopes to track masers鈥攂rilliant microwave sources鈥攃ircling
a black hole in a distant galaxy.
Having measured the masers鈥� speeds from their Doppler shifts, simple
trigonometry gave their distance as 23.5 million light-years. This is 15 per
cent closer than other estimates based on signals from variable stars called
Cepheids (Nature, vol 400, p 539).
As astronomers generally use Cepheids as a cosmic yardstick, the finding has
serious implications. 鈥淚f true,鈥� says Herrnstein, 鈥渢hen distant galaxies are 15
to 20 per cent closer, and the Universe is 15 to 20 per cent younger.鈥�
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