Released in 2002 as part of a coin collection commemorating 500 years of the discovery of St Helena. 
 
This coin commemorates the astronomer who built an observatory on the island in 1676–77, to catalogue the southern celestial hemisphere and record a transit of Mercury across the Sun.
 
Please note the production of this coin is a different design to the standard decimilsed 50p. This coin is the same size as a standard £5 coin/commemorative Crown and was not intended for circulation, purely for commemorative purposes.
 
Obverse: Queen Elizabeth Portrait (Raphael David Maklouf)
Reverse: Bust 1/4 left, ship HMS Paramour and a comet.