In 1742 he graduated from Trondheim Cathedral School and attended the University of Copenhagen where he studied medicine and took a Bachelor's degree in 1747.

He studied natural history with Linnaeus and chemistry and metallurgy with Johan Gottschalk Wallerius (1709–1785).

Ascanius undertook a study trip in the years 1753 to 1758, visiting the Netherlands, England, France, Italy and Austria.

[2][3][4] [5] After returning from his European study trip, in 1759 Ascanius was appointed professor of natural history at the Royal Danish Academy of Fine Arts which was established at Charlottenborg at Copenhagen in 1754.

He died unmarried on 4 June 1803 and is buried in the crypt of Frederick's German Church in Christianshavn.