Liisi Oterma (; 6 January 1915 – 4 April 2001) was a Finnish

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

, the first woman to get a

Ph.D. A Doctor of Philosophy (PhD, Ph.D., or DPhil; Latin: or ') is the most common degree at the highest academic level awarded following a course of study. PhDs are awarded for programs across the whole breadth of academic fields. Because it is a ...

degree in

astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

in Finland. She studied mathematics and astronomy at the

University of Turku sv, Åbo universitet , latin_name = Universitas Aboensis , image_name = University of Turku.svg , motto = ''Vapaan kansan lahja vapaalle tieteelle'' , established = 1920 , type ...

, and soon became Yrjö Väisälä's assistant and worked on the search for minor planets. She obtained her masters 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. 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. Oterma was interested in languages and spoke German, French, Italian, Spanish,

Esperanto Esperanto ( or ) is the world's most widely spoken constructed international auxiliary language. Created by the Warsaw-based ophthalmologist L. L. Zamenhof in 1887, it was intended to be a universal second language for international communi ...

, 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. 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. She discovered or co-discovered several

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...

s, including periodic comets 38P/Stephan-Oterma,

39P/Oterma 39P/Oterma is a currently inactive List of periodic comets, periodic comet with an orbital period of nearly 20 years that stays outside the orbit of Jupiter. The comet nucleus, nucleus has a diameter around 4–5 km. It was last observed in Augu ...

and

139P/Väisälä–Oterma 139P/Väisälä–Oterma is a periodic comet in the Solar System. When it was discovered in 1939 it was not recognized as a comet and designated as asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of astero ...

. She is also credited by the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function ...

(MPC) with the discovery of 54

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...

s between 1938 and 1953, and ranks 153rd on MPC's all-time discovery chart. The Hildian asteroid

1529 Oterma 1529 Oterma, provisional designation , is a reddish, rare-type Hildian asteroid from the outermost region of the asteroid belt, approximately 56 kilometers in diameter. It was discovered on 26 January 1938, by Finnish astronomer Yrjö Väisälä ...

, discovered by Finnish astronomer Yrjö Väisälä in 1938, was named in her honour.

Minor planets discovered

References

{{DEFAULTSORT:Oterma, Liisi 1915 births 2001 deaths 20th-century women scientists 20th-century astronomers Discoverers of asteroids Discoverers of comets * Finnish astronomers Women astronomers Astronomy-optics society