The International Year of Astronomy was a year-long celebration of astronomy in 2009 that coincided with the 400th anniversary of the first recorded astronomical observations made by Galileo Galilei (1564–1642) with a telescope and the publication of Johannes Kepler's (1571–1630) Astronomia nova. Partaking in the celebrations, the Austrian Mint made astronomy the subject of that year's 25 euro coin. Both sides were designed by Herbert Wähner. The color of the niobium pill in the center is golden yellow to represent the sun.

Each coin contains 9 g of 900 Fine Silver in its outer ring and 6.5 g of 998 pure niobium. Niobium was chosen for the core due to its workability as a coinage metal and its low reactivity (which prevents its corroding where it comes in contact with the silver ring). Each piece is encapsulated, boxed and comes complete with a numbered certificate guaranteeing its authenticity.


The back side of the moon makes up the colored center of the obverse, with portions of a satellite additionally being in the center and also in the silver ring. The words "rückseite des mondes", translating from German as "back of the moon", are engraved from the upper left edge of the center to the lower right, arching near the top. Wähner's signature, "H WÄHNER", is engraved between the end of the word "mondes" and the depiction of the satellite. The earth is featured at the left side of the silver ring while a stylized sun emitting light rays extending to the other side of the obverse is depicted at the right side.

republik österreich
rückselte des mondes
25 euro


A portrait of a facing Galileo Galilei is shown at the left-hand side of the reverse. Next to his likeness is an illustration of a Galilean telescope, and in the background is one of Galileo's first drawings of the surface of the moon. A space telescope is shown at the top of the silver ring, along with a stylized sun similar to the one on the obverse and an image of Saturn. Also featured along the ring are a radio telescope, the Isaac Newton Telescope, the observatory in Kremsmünster Abbey, and a modern telescope. The inscription "jahr der astronomie", which translates to "year of astronomy", is written around the circumference of the golden center, while the date "2009" is printed just above the niobium pill and the year "1609" is featured at the very bottom of the coin.

Galileo Galilei (1564–1642) was an Italian polymath: astronomer, physicist, engineer, philosopher, and mathematician, he played a major role in the scientific revolution of the seventeenth century. He has been called the "father of observational astronomy", the "father of modern physics", the "father of scientific method", and the "father of science".

Galileo's championing of heliocentrism and Copernicanism was controversial during his lifetime, when most subscribed to either geocentrism or the Tychonic system. He met with opposition from astronomers, who doubted heliocentrism because of the absence of an observed stellar parallax. The matter was investigated by the Roman Inquisition in 1615, which concluded that heliocentrism was "foolish and absurd in philosophy, and formally heretical since it explicitly contradicts in many places the sense of Holy Scripture." Galileo later defended his views in Dialogue Concerning the Two Chief World Systems, which appeared to attack Pope Urban VIII and thus alienated him and the Jesuits, who had both supported Galileo up until this point. He was tried by the Inquisition, found "vehemently suspect of heresy", and forced to recant. He spent the rest of his life under house arrest. While under house arrest, he wrote one of his best-known works, Two New Sciences, in which he summarized work he had done some forty years earlier on the two sciences now called kinematics and strength of materials.

jahr der astronomie


25 Euro

Silver Niobium Coin
International Year of Astronomy

Subscribe series
KM# 3174
Type Commemorative Issue (Non-circulating)
Material Bi-Metallic
Ring Silver
Center Niobium
Weight 16.5 g
Diameter 34 mm
Thickness 2.55 mm
Shape round
Alignment Medal
Austrian Mint

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