Measuring the Hubble Constant (IMAGE)

NASA/Goddard Space Flight Center

Measuring the Hubble Constant

Caption

This illustration shows 3 steps astronomers used to measure the universe's expansion rate (Hubble constant) to an unprecedented accuracy, reducing the total uncertainty to 2.3 percent. The measurements streamline and strengthen the construction of the cosmic distance ladder, which is used to measure accurate distances to galaxies near to and far from Earth. The latest Hubble study extends the number of Cepheid variable stars analyzed to distances of up to 10 times farther across our galaxy than previous Hubble results.

Credit

NASA, ESA, A. Feild (STScI), and A. Riess (STScI/JHU)

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