Oskar Backlund was educated at Uppsala and Stockholm, Sweden, and lectured at the University of Uppsala in 1875. He became an astronomical assistant at Stockholm Observatory in 1876, but later moved to Pulkova Observatory near Petrograd (now Sankt-Peterburg), Russia, becoming Director of the observatory in 1895. He was elected an Academician of Petrograd and, in 1911, a fellow of the Royal Society of London.
Backlund did extensive research on the progressive decrease in the period of Encke's comet, at first testing the hypothesis that it might move in a resisting medium. This seemed not to be the case and he formulated a theory of perturbations of the comet's orbit to account for the phenomenon. In addition to a number of papers he published a four volume book on the comet in 1892-1894 and another three volume work, La comete d'Encke, 1891-1908, in 1908-1911. For his work on this comer he was awarded the gold medal of the Royal Astronomical Society. Some papers by him (1898, 1899), as well as a book (1900), dealt with the orbits of the minor planets. Other papers dealt with the mass of Mercury (1886), the three body problem (1887), Jupiter's satelites (1887), a solar eclipse observed at Novaja Zemlja on 8 August 1896, and many others topics.
In 1905 Backlund visited South Africa to attend the joint meeting of the British and South African Associations for the Advancement of science. Although not listed as a member of the British Association he served as joint vice-president of its Section A (mathematical and physical sciences) at this meeting, and read a paper in Cape Town on "Geodetic and gravitational observations in Spitzbergen". The paper was of local interest as the geodetic survey of southern Africa was still in progress, and H.M. Astronomer at the Cape, David Gill*, who planned and directed the work, hoped that the local survey would eventually extend along the 30th meridian East right through Africa to link up with the geodetic survey of Europe, which extended to Spitzbergen. At a special graduation ceremony of the University of the Cape of Good Hope on 17 August 1905, Backlund was one of several delegates who received an honorary Doctor of Science degree.
At this time Backlund was organising a programme to study the variations in latitude, in which he wished to involve observatories in both the northern and southern hemispheres. It seems that he first approached Gill for assistance. However, the Transvaal Observatory - then a meteorological observatory in Johannesburg directed by R.T.A. Innes* - was authorised to take part in the project and in 1906 the Russian government, via Backlund, lent the observatory a 67mm transit instrument for the work. This was the observatory's first astronomical instrument. The programme ran for a number of years, but the telescope was also used to maintain a time service for the Transvaal until the time signals of the Paris Observatory could be received by radio.
According to his obituary, 'Oskar Backlund was, by consent of all who knew him, the most lovable man in the world', a man with a charming personality, affectionate simplicity, slow delightful speech, solemn wit, and kindly judgments.