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Ire BruntFinnish astronomer, optician and geodesist, professor, academician
Date of Birth: 06.09.1891
Country:  Finland |
Content:
Early Life and Education
Yrj? V?is?l?, a Finnish astronomer, optician, and geodesist, was born on September 6, 1891, in Joensuu, Finland, which was then part of the Russian Empire. He earned his degree from the University of Helsinki.
Career
After graduating, V?is?l? worked as a mathematician for an insurance company before joining the Finnish Geodetic Institute from 1918 to 1923. In 1923, he moved to the University of Turku, where he became a professor of physics in 1925 and a professor of astronomy from 1927 to 1961.
In 1951, V?is?l? established the Astronomical and Optical Observatory (Tuorla Observatory) at the University of Turku, serving as its director for the rest of his life. He was elected a member of the Finnish Academy of Science and Letters and the Academy of Finland in 1951.
Contributions
V?is?l? developed innovative methods for quality control and production of optical components. He conceived the idea of using a specially deformed plate to correct the field of a reflecting telescope's mirror, but this proposal remained unpublished. Upon learning of B. Schmidt's similar proposal, V?is?l? further refined the idea, proposing a correcting lens in front of the photographic plate.
V?is?l? also pioneered the use of liquid mercury mirrors. During large-scale triangulation measurements in Finland in the 1920s and 1930s, he suggested using flashing lights on balloons or rockets to create distant triangulation points. This concept was not realized until 1959 and later became the basis for modern global and local satellite geodesy.
V?is?l? devised a method for determining the Earth's axis of rotation using a zenith telescope. This instrument enabled Tuorla Observatory to maintain the most accurate measurements of the North Pole's position during the 1960s.
Astronomy and Astrophysics
Under V?is?l?'s leadership, the observatories of Turku and Tuorla engaged in comet and asteroid searches. His team discovered a total of 7 comets and 807 asteroids. V?is?l? developed a novel method for detecting moving objects by photographing the same area of the sky twice with a time difference and comparing the images.
Among V?is?l?'s significant discoveries were two periodic comets, 40P/V?is?l? and 139P/V?is?l?-Oterma. He personally discovered 128 asteroids, some of which he named after his friends to commemorate their birthdays.
Later Years
Yrj? V?is?l? died on June 28, 1971. He left behind a lasting legacy in astronomy, geodesy, and optics. His innovative ideas and groundbreaking discoveries have significantly advanced our understanding of the universe.
