<a href="https://en.wikipedia.org/wiki/Radiation" id="mw_A" rel="mw:WikiLink" title="Radiation">Radiation</a> from an explosion on the <a href="https://en.wikipedia.org/wiki/Magnetar" id="mw_Q" rel="mw:WikiLink" title="Magnetar">magnetar</a> <a class="mw-redirect" href="https://en.wikipedia.org/wiki/SGR_1806-20" id="mw_g" rel="mw:WikiLink" title="SGR 1806-20">SGR 1806-20</a> reaches Earth. It is the brightest <a class="mw-redirect" href="https://en.wikipedia.org/wiki/Extrasolar" id="mw_w" rel="mw:WikiLink" title="Extrasolar">extrasolar</a> event known to have been witnessed on the planet.