Astronomy: Twinkle, Twinkle 3C-273

Seen through the finest optical telescopes, the five nondescript points in the sky looked like ordinary stars. To radio astronomers though, they sounded uncommonly noisy. For some strange reason they were all exceptionally powerful radio transmitters—electronic extroverts among the quiet billions of other stars that keep almost perfect radio silence.

Astronomers were stumped by the bright, mysterious bodies. What was causing all the radio noise? Even photographs of the stars' spectra—all the wave lengths of emitted light, from red to violet—were no help. A star's spectrum is its individual signature, but...

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