50 Euros - Albert II Auguste Picard

Auguste Piccard — physicist, balloonist, and deep-sea pioneer — reached the stratosphere in a pressurized gondola of his own design in 1931, becoming the first person to observe the curvature of the Earth with his own eyes. Belgium issued commemorative gold in his honor not merely for the ascent, but because Piccard was a genuinely polymathic figure: the same engineering logic that got him to 15,781 meters eventually drove his bathyscaphe program, culminating in his son Jacques touching the bottom of the Mariana Trench in 1960.