Skywatch

  • November 9, 2006

    Episode 66: A Bigger Universe?

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    The expansion rate and scale of the universe are fundamental quantities that astronomers strive to nail down. As of 2001, the expansion rate of the universe, and therefore the distance scale, was pretty well determined. New observations of a binary star system in a nearby galaxy, M33, has highlighted the difficulty of measuring vast distances. The stars' dimness indicates that the system is 15 percent farther away than expected - about 3 million light-years away, instead of 2.6 million light-years. The discovery could call into question the rate of expansion of the universe, known as the Hubble constant. If the new analysis survives the test of time, it could be that the universe is 15% larger and older than previously thought.