SGR 1806-20 is a magnetar, a particular type of neutron star. It was discovered in 1979 and has been identified as a soft gamma repeater. SGR 1806-20 is located about 14.5 kiloparsecs (50,000 light-years) from Earth on the far side of the Milky Way galaxy in the constellation of Sagittarius. It has a diameter of no more than 20 kilometres (12 mi) and rotates on its axis every 7.5 seconds (30,000 km/h rotation speed at the surface). As of 2012, SGR 1806-20 is the most highly magnetized object ever observed, with a magnetic field over 1015 gauss (1011 tesla) in intensity (compared to the Sun's 1–5 gauss). SGR 1806-20 has a magnetic field that is 1-2 quadrillion (short scale) times stronger than that of the Earth.