Excerpt from Chapter One, "Mysteries of the Universe"

Objects Strange and Wonderful, Page 3 of 5

After all possible human-made signals were ruled out, there seemed to be no reasonable explanation. Indeed Bell and her colleagues met more than once to discuss the proper way to make an announcement: "Little green men," as they wryly put it, or some sort of extragalactic neighbors were sending us a message.

Such speculations later attracted the attention of the popular press, but the level-headed Bell was relieved when she found a more rational, but no less wondrous, explanation.

A second signal was discovered, pulsing at the unvarying rate of one and one-quarter seconds on the opposite side of the sky from the first signal. The likelihood of two such alien transmitters was very slim. Then a clue came from physicists and their discovery of what happens to atoms subjected to incredibly intense pressure: they collapse into very dense matter. The source of the metronomic signals turned out to be a star that had crumpled from its gigantic mature form into a chunk about the size of an asteroid. When a giant star runs out of nuclear fuel, it first implodes, then explodes into a spectacular supernova. In the case of pulsars, the residue includes a neutron star, usually no more than six miles in radius but with more total mass than our sun. As the name neutron star might suggest, all of its electrons are crammed smack into its protons, thus forming neutrons with absolutely no open space in between. As this odd compact sphere rotates it emits a powerful magnetic field in a narrow beam that sweeps across the galaxies, pinging regularly on earth's radio telescopes. Some pulsars have been clocked spinning as fast as one thousand times a second. By discovering these previously unimagined stars, the new field of radio astronomy proved itself capable of revealing cosmic wonders where not a thing could be detected by human eye or optical telescope.

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