He was born in Länghem, in
Västergötland,
Sweden and graduated from
Uppsala University in 1872. After getting his doctorate in 1875, he emigrated to Russia in 1876. He worked at
Dorpat Observatory, in today's
Tartu,
Estonia, and then in 1879 worked at
Pulkovo Observatory, becoming director of the observatory from 1895 until his death. He specialized in
celestial mechanics, and notably worked on calculating the orbit of
Comet Encke, taking into account the perturbations of various planets. He used observations of Comet Encke to try estimate the mass of
Mercury. Russian sources sometimes referred to the comet as Comet Encke-Backlund. He also carried out
geodesic studies in
Spitzbergen from 1898 to 1900. He became a member of the
Saint Petersburg Academy of Sciences in 1883, member of the
Royal Swedish Academy of Sciences in 1897 and
Fellow of the Royal Society in 1911. He was elected a Foreign Honorary Member of the
American Academy of Arts and Sciences in 1914. ==Family==