On August 24, 1998, there was an explosion on the sun as powerful as a hundred million hydrogen bombs. Earth-orbiting satellites registered a surge of x-rays. Minutes later they were pelted by fast-moving solar protons. Our planet's magnetic field recoiled from the onslaught, and ham radio operators experienced a strong shortwave blackout.
None of these things made headlines. The explosion was an "X-class" solar flare, and during years around solar maximum, such as 1998, such flares are commonplace. They happen every few days or weeks. The Aug. 24th event was powerful, yet typical.
A few days later--no surprise--another blast wave swept past Earth. Satellites registered a surge of x-rays and gamma-rays. Hams experienced another blackout. It seemed like another X-class solar flare. Except for one thing: this flare didn't come from the sun.
It came from outer space.
"The source of the blast was SGR 1900+14, a neutron star about 45,000 light years away," says NASA astronomer Pete Woods. "It was the strongest burst of cosmic x-rays and gamma rays we've ever recorded."
I really don't like to think about what the effect would have been if it had only been a few hundred light years away. Enough to sterilise the surfaces of all planets orbitting nearby star systems, anyway. And any Interstellar travellers had better have their SPF 5 trillion sunscreens on, or just a kilometre thickness of lead shielding.
The sooner we get off this rock and start spreading out a bit, the better.
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