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The Uncharted Universe

Astronomical phenomena on phenomenal coins

The Uncharted Universe comprises three coins the likes of which have never previously existed. This ambitious series lets you travel to the deepest depths of the universe and take a close look at three mind-boggling astronomical phenomena, the first of which is The Milky Way (2021).

Gentle S shape
Curved in a similar way to our home galaxy, the first coin in the series allows you to roam into the vastness of the Milky Way. One half of the coin is convex and the other is concave; viewed in profile, it has a gentle shape, not unlike a wave.

The second coin, The Black Hole, takes you beyond the "event horizon" of this unique phenomenon. (2022).

Funnel shape
On the obverse of The Black Hole, a cone rises from the flat silver surface, representing the curvature of space-time. The black hole vortex phenomenon is illustrated on the coin’s reverse in the shape a funnel. Get up close and personal with the Holy Grail of theoretical physics by taking a peek into a black hole.

The Neutron Star coin, the third and final coin in The Uncharted Universe, shows how a massive star, combined with gravitational collapse, becomes one of the densest stellar objects in the universe (2023).

Hemisphere shape
In the centre of The Neutron Star coin, a hemisphere curves inwards on one side and outwards on the other. Neutron stars are still something of a mystery, but this little masterpiece makes them a lot more tangible.

With the help of these three coins, you will reach the final frontier, beyond which lie the unknown and the unexplored.

Silver makes a great gift. So does The Uncharted Universe, whether for children or adults with a soft spot for astronomy.


Series Overview


2021:  The Milky Way 
2022:  The Black Hole
2023:  The Neutron Star

Mintage in Proof quality: 30,000 pieces


20 Euro silver coin "The Neutron Star"

Reach for the stars!

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. 

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.

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.




Face Value

20 Euro


34 mm


Silver Ag 925


22.42 g

All products in the series

The neutron star

The Black Hole

    Silbermünze Milchstraße Rückseite

The milky way

    Sammelkassette Faszination Universum

collector case