Astronomer. Born and educated in Dundee. Henderson began as a lawyer's clerk. However, his keen interest in astronomy led to his appointment as H.M. Astronomer at the Cape of Good Hope by King William IV (1831). Illness caused him to return to Scotland after only two years. He was appointed the first Astronomer Royal in Scotland (1834), and worked diligently at the Calton Hill Observatory in Edinburgh for ten years, making more than 60,000 observations of star positions.
Henderson was the first person to measure the distance of a star. Using parallax he computed the remoteness of Alpha Centauri, now known to be the nearest star to the Sun. However, Henderson lost much of the credit for his work because he did not publish his results until 1839.
He died in Edinburgh.