Seeing red: in distant galaxies that shine with a ruddy glow are stars that look older than the universe that begat them.(Out There)

Publication: Natural History

Publication Date: 01-MAR-05

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COPYRIGHT 2005 Natural History Magazine, Inc.

To an astronomer, color is just as important as it is to an interior designer--though in quite a different way. To both, what the eye perceives as red is light of relatively long wavelength; the wavelength of the light the eye perceives as blue is relatively short. The designer, however, seeks the complex balance of wavelengths that, like the notes in a musical chord, gives a unified color tone to create a mood--a crimson, say, a scarlet, or a cardinal. The astronomer's colors are equally complex, but here it is the parts that are important, the individual, single-wavelength colors into which the spectrum of a distant star or galaxy can be analyzed.

The many colors of starlight, it turns out, can reveal a great deal about a star--including its age. Statistically speaking, long-lived stars emit more long-wavelength light than short-lived stars do. The...

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