In 2001 Japanese researcher Yoshitsugu Kunugiyama surmised that the cover illustration Saint-Exupéry painted for "Le Petit Prince" deliberately depicted a stellar arrangement created to celebrate the author's own centennial of birth. According to Kunugiyama, the cover art chosen from one of Saint-Exupéry's watercolour illustrations contained the planets Saturn and Jupiter, plus the star Aldebaran, arranged as an isosceles triangle, a celestial configuration which occurred in the early 1940s, and which he likely knew would next reoccur in the year 2000. Saint-Exupéry possessed superior mathematical skills and was a master celestial navigator, a vocation he had studied at Salon-de-Provence with the "Armée de l'Air" (French Air Force).