Via Phil Plait at Bad Astronomy:
Astronomers have announced they found a new magnetar, named SGR 0501+4516, and it’s only 15,000 light years away. It turns out to be dark most of the time, emitting very little energy, which is how it escaped detection. But it had an outburst last year that lasted four months, allowing scientists time detect it and to get a good long look at it.
This is shocking, because magnetars are neutron stars with a crust, that produce insanely strong magnetic fields; they also produce insane amounts of x-ray radiation whenever they undergo a “star-quake” and the crust breaks causing some extremely violent subatomic reactions. At 15kly away, we’re safe. But a giant burst from a magnetar at 50kly away actually caused effects that were measurable on our atmosphere, so if this (admittedly smaller and darker) one were to undergo a similar event (at 32 on the Richter scale apparently!), it could very well do some real damage. Not, like, blowing the atmosphere off our planet, but it could fry some satellites and maybe damage the atmosphere somewhat.