She studied mathematics and astronomy at the University of Turku, and soon became Yrjö Väisälä's assistant and worked on the search for minor planets. She obtained her master's degree in 1938. From 1941 to 1965, Oterma worked as an observer at the university's observatory. She obtained her PhD in 1955 with a dissertation on telescope optics. She was the first Finnish woman to obtain a PhD in astronomy.[1]
In 1959, Oterma became a docent of astronomy and from 1965 to 1978 a professor in University of Turku. In 1971, she succeeded Väisälä as the director of the Tuorla Observatory. She was director of the astronomical-optical research institute at the University of Turku from 1971-1975.[1]
Oterma was interested in languages and spoke German, French, Italian, Spanish, Esperanto, Hungarian, English and also Arabic, for example. Oterma's original plans were to study Sanskrit, but it was not offered at the University of Turku, and the choice was ultimately focused on astronomy.[1]
Oterma was quiet, modest in nature, and fearful of publicity. Anders Reiz, a professor at the Copenhagen Observatory, among others, said Oterma was “silent in eleven languages”. Oterma avoided appearing in photographs, and there are only a handful of pictures of her.
