A spokeswoman at Carnegie Institution for Science (CIS) in Pasadena, California, has confirmed to Nature that Allan Sandage, an influential US astronomer who once worked as the assistant to Edwin Hubble, has passed away. He was 84. No further details on Sandage’s death were available from CIS press office, which is now preparing an obituary press release.

From the time of his work with Hubble to his later investigations using data from the Hubble Space Telescope (HST), Sandage’s career spanned the decades between astronomers’ first precise measurements of the distances to remote galaxies to the modern discovery that a mysterious dark energy is driving them apart from one another. He played a key role in the initial discovery of quasars and produced a definitive photographic atlas of galaxies.

Sandage was well known for his precision observations of Cepheid variable stars, which he used to determine the age and expansion rate of the Universe – the so called Hubble constant. For much of his career he was the leading proponent of an older, larger universe with a relatively low Hubble constant of about 50. Subsequent measurements with the HST have since yielded a figure around 70. (A number of apparent contradictions related to the age of the Universe were resolved after 1998 when it was understood that the expansion of space is accelerating due to dark energy.)

Sandage received his PhD at the California Institute of Technology in 1953 and from 1952 onward was on staff at the celebrated Mount Wilson and Mount Palomar observatories, now part of the Carnegie Institution. Among other honors, he was awarded the US National Medal of Science in 1970, the Bruce Medal (from the Astronomical Society of the Pacific) in 1975 and the Crafoord Prize (from the Royal Swedish Academy of Sciences) in 1991.

Photo courtesy Carnegie Insitution for Science.

Jointly posted with Ivan Semeniuk