Column: Especially when it comes to outer space, there's a lot to be learned from reexamining old science.
Gemini Observatory/Dana Berry, SkyWorks Digital Animation
While astronomers always hope to find exotic new phenomena, they know it pays to take a fresh look at things well known. Three recent examples make this point.
Cosmic measuring tape
A search of previously published observations has come up with a better way of measuring some cosmic distances. Ofer Lahav at Britain's University College in London said it "will have profound implications
for understanding the basic properties of our universe."
Dr. Lahav explained in the journal Nature that such measurements can help refine our understanding of the distribution and makeup of the cosmos. He was commenting on a study published in a astrophysical journal. Lead author Jonathan Bird of Ohio State University then updated the research in early June at a meeting of the American Astronomical Society in Pasadena, Calif.
Astronomers have long used giant stars called Cepheid variables for the first leg of their cosmic distance scale. The rate at which the star's light pulses indicates the star's intrinsic brightness. Knowing that, and seeing how faint the star appears from Earth, measures the star's distance. It's the so-called "standard candle" effect. This has enabled highly accurate distance measurements out to about 100 million light years.
Searching the astronomical literature, Mr. Bird and his colleagues have identified 18 examples of a type of Cepheid that can act as a standard out to 300 million light years. Extending Cepheid accuracy to three times its former reach will refine our knowledge of the universe's expansion. It will also help in calibrating some other types of distance measurement that overlap the Cepheid range but have a much farther reach.