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20 Kroner - Margrethe II Ole Rømer and The Speed of Light
| Issuer | Danmarks Nationalbank |
|---|---|
| Year | 2013 |
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| Value | 20 Kroner |
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| Obverse description | Log in to see details |
|---|---|
| Obverse script | Latin |
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| Reverse description | The reverse commemorates Danish astronomer Ole Rømer and his landmark 1675 determination of the speed of light, forming part of Denmark's scientific series. A stylized design evoking the propagation of light is depicted in the central field, accompanied by the inscription OLE RØMER and LYSETS HASTIGHED (Speed of Light) along with the date 1675. The denomination 20 KRONER appears within the legend. |
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| Additional information |
This piece belongs to Denmark's ongoing commemorative 20-krone program, and the subject is a genuine point of national pride: Ole Rømer, the 17th-century Danish astronomer who in 1676 became the first person to demonstrate that light travels at a finite speed. Working at the Paris Observatory and observing discrepancies in the predicted eclipses of Jupiter's moon Io, Rømer calculated a value for the speed of light that came within about 26% of the accepted modern figure — a remarkable result given the instruments available.
Rømer made his observations while in French royal service under Louis XIV, which placed a Danish scientific achievement firmly within the French academy's records.