Nov. 10, 1861: The birth of Robert Innes

Today in the history of astronomy, Proxima Centauri’s discoverer is born. | Published: November 10, 2026 Our Sun and its 10 nearest neighbors are shown in this diagram, with their relative sizes to scale. Credit: Astronomy: Roen Kelly Born Nov. 10, 1861, in Scotland, Robert Thorburn Ayton Innes would reshape our understanding of our cosmic neighborhood when he discovered our nearest stellar neighbor, Proxima Centauri, in 1912. Innes suspected that Alpha Centauri, a binary system made up of Alpha Centauri A (Rigil Kentaurus) and Alpha Centauri B (Toliman) and then thought to be the nearest stars to Earth (besides the Sun) – had a third member. The director of the Union Observatory in Johannesburg, South Africa, Innes began a systematic survey for the missing companion star, comparing five years’ worth of photographic plates using a blink-microscope. He noted that a small, faint, red star seemed to move in concert with Alpha Centauri; further research revealed it was in fact closer to Earth than its companions. Innes announced the find in 1915, and later named the body Proxima Centauri – proxima meaning “nearest” in Latin. Elisa Neckar is senior production editor of Astronomy magazine, and the editor of the Today in the History of Astronomy feature on Astronomy.com.