 On 30 June 1973 he was part of an international team of astronomists that travelled to Kenya to observe the longest solar eclipse of the 20th century.As a university student, van Ypersele had an important social involvement

Van Ypersele carried out a PhD research in climatology.At the initiative of professor André Berger the "Institut d’Astronomie et de Géophysique Georges Lemaître " of the UCLouvain had started to study the impacts of changes in concentration of greenhouse gasses on the evolution of the Earth's climate.