from the blast-from-the-past dept.
The Bad Astronomer writes "Five years ago today (December 27, 2004), a vast wave of high-energy gamma and X-rays washed over the Earth, blinding satellites and partially ionizing the Earth's atmosphere. The culprit was a superflare from the magnetar SGR 1806-20, located 50,000 light years away. The energy released was mind-numbing: in one-fifth of a second, this supercharged magnetic neutron star blasted out as much energy as the Sun does in 250,000 years!"
We warn the reader in advance that the proof presented here depends on a
clever but highly unmotivated trick.
-- Howard Anton, "Elementary Linear Algebra"