Cosmic Bomb

It wasn't long ago that astronomers had just a handful of heavenly bodies to think about: stars, planets, comets and not much else. But then along came quasars, then pulsars, then black holes--bizarre objects that have made the universe a decidedly more interesting place.

Now another oddball has joined this menagerie of improbable cosmic beasts. On Aug. 27, a burst of electromagnetic energy smashed against the earth's atmosphere, ripping apart air molecules, disrupting radio communications and knocking a couple of satellites temporarily offline. The most likely source of the power surge, scientists announced last week: a starquake on a new kind of celestial object called a magnetar.

A magnetar is a star that has run out of fuel and collapsed to form a neutron star--a ball of matter just a dozen miles across, so dense that a teaspoonful weighs tens of millions of tons. In rare instances, a neutron star can generate a magnetic field strong enough to shatter the star's metallic surface, sending high-energy X rays and gamma rays blasting into space.

The X rays and gamma rays recorded by orbiting observatories let astronomers know just how strong the magnetic field on this magnetar, dubbed SGR1900+14, is: about 800 trillion times as strong as the field that makes a compass work on Earth.

Fortunately for our planet, SGR1900+14 is 20 light-years away. Its radiation was so weakened by the time it got here that its X rays and gamma rays couldn't penetrate the atmosphere. No one was harmed--except, perhaps, for textbook publishers, who are suddenly, through no fault of their own, out of date.

--By Michael D. Lemonick