20 Euro Silver Neutron Star Coin P
Among the densest stellar objects in the universe, neutron stars are heavier than the sun itself. A superb representation of this unique galactic phenomenon, this little beauty weighs considerably less. Featuring a semi-sphere in its centre that curves inwards on one side and outwards on the other, the last coin in *The Uncharted Universe* series is designed to be a simplified representation of that unique galactic phenomenon – the neutron star. **Reach for the Stars!** There are thought to be up to one billion neutron stars in the Milky Way. This figure is obtained by estimating the number of stars that have undergone a supernova explosion, a spectacular explosion of a massive star. Combined with gravitational collapse, this creates a compact and super-dense object known as a neutron star. After black holes, neutron stars are the densest stellar objects in the universe. Even denser than atomic nuclei, which is a good way to think of them, neutron stars are heavier than the Sun itself: a teaspoonful of neutron star would weigh as much as 1,000 Cheops pyramids. Neutron stars can rotate at very high speed – up to 700 revolutions per second – and have a magnetic field 12 to 15 orders of magnitude stronger than that of the Earth, which is a thousand to a million times stronger than the strongest man-made magnetic fields ever produced. **Coin motif** The words ‘crust’ and ‘core’ are marked in German on the coin’s obverse. ‘Crab pulsar’ is the name of a neutron star that was created from a supernova in the year 1054, while ‘1,4 M ’ refers to the neutron star’s solar mass, ‘30rps’ to its rotation speed per second and ‘r~10km’ to its radius. On the coin’s reverse, the neutron star bulges through a coloured imprint and a stylised representation of its magnetic field. As far as the exact composition of neutron stars is concerned, many things are still a mystery to scientists, but it is hoped that new insights will be gained by studying the expansion of the universe.