https://www.theregister.co.uk/2018/06/14/supernova_magnetic_field_research/ > How to measure a magnetic field that's very long way away, and is very, very weak. An international group of boffins have announced that they figured out how. > The magnetic field in question belongs to a distant supernova remnant, Supernova 1987A, 168,000 light years from Earth. While the supernova exploded in 1987, its remnants remains a favourite observation target.