20 Euro Silver Cat's Eye Nebula Coin P
**Cosmically clear cut** Not just impressive, the discovery of the Cat’s Eye Nebula by the German-British astronomer Wilhelm Herschel (1738–1822) on 15 February 1786 helped turn what had been merely an assumption in physics into an immutable law. Indeed, despite appearing mysteriously misty, veiled and softly focused on this extraordinarily shaped and coloured coin, the Cat’s Eye Nebula, also known as NGC 6543, has provided modern science with crystal-clear insights. Such a planetary nebula is formed when a star similar to our Sun, with no more than a few solar masses, reaches the end of its activity and becomes a red giant. The core contracts, the star’s envelope swells and pulsates, and with each pulse parts of the star’s atmosphere and outer layers are blown into space. The ejected matter is gaseous, has a temperature of about 10,000 kelvin and moves away from the star in all directions at several dozen kilometres per second. NGC 6543 was the first planetary nebula to be studied in detail using spectroscopy. Making it possible for scientists to deduce its composition from the light emitted by the celestial body, this contributed to the insight that all observable celestial bodies consist of the same chemical elements as the Earth. This, in turn, led to an enormous gain in knowledge as it supported the scientific assumption that the laws of physics are the same throughout the universe. To date, no discovery has been made that casts the slightest doubt on this assumption. Before the (cosmic) law, we are all equal. **Coin motif** Flat in the centre, *Cat’s Eye Nebula* curves upwards towards the edge in several waves. The main motif on the coin’s obverse is a stylised representation of the Cat’s Eye Nebula. NGC 6543 refers to the New General Catalogue from 1888, which contains all deep sky objects known at the time of its publication. The inscription 3300 Lj indicates the distance of the Cat’s Eye Nebula from Earth. The coordinates Right Ascension: 17h 58m 33.4s and Declination: +66° 37´ 59’’ indicate the position of the celestial body. The coin’s reverse is printed with a coloured interpretation of the Cat’s Eye Nebula.