Researchers using a sophisticated testbed at Caltech’s
Palomar Observatory near San Diego, Calif., have achieved the
best-ever distance measurement to a type of star known as a
Cepheid variable. These results improve the “cosmic yardstick”
used to infer the size and shape of the universe.

In the September 28 issue of the journal Nature, astronomers
from NASA’s Jet Propulsion Laboratory; the California Institute
of Technology; and the JPL/Caltech Infrared Processing and
Analysis Center, all in Pasadena, determined a distance to the
star Zeta Geminorum in the Gemini constellation of 1,100 light
years. The improvement was made possible by the Palomar Testbed
Interferometer, designed and built by JPL researchers. The
device combines light gathered by two telescopes to produce a
very sharp image normally obtainable only with a much larger

Details on this discovery and the testbed are available at