ann18048 — Announcement

IAU Resolutions being presented at the GA 2018
4 October 2018
Electronic IAU vote on a suggested renaming of the Hubble law

During its XXX General Assembly in Vienna (in August 2018), the International Astronomical Union (IAU) put forward a draft resolution to rename the Hubble law as the “Hubble–Lemaître law”. The resolution was proposed to recognise Lemaître’s research on the expansion of the Universe, and to pay tribute to both Lemaître and Hubble for their fundamental contributions to the development of modern cosmology. This resolution has now been put to all IAU Junior and Individual Members via an electronic vote.

To acknowledge the fundamental scientific contributions of both Georges Lemaître and Edwin Hubble to the scientific theory of the expansion of the Universe [1] [2] [3] [4], the International Astronomical Union (IAU) has proposed a resolution (Resolution B4) that would have the effect of renaming the Hubble law as the “Hubble–Lemaître law”. This resolution was put forward after a period of extensive consultation with the astronomical community and it was one of the most intensely discussed proposals presented at the XXX General Assembly of the IAU.

A straw poll conducted by the IAU General Secretary at the General Assembly indicated that 74 per cent of the 385 attending Individual Members were in agreement with the proposed resolution. However, given the importance of the Hubble law, the IAU Executive Committee decided to put Resolution B4 to an electronic vote before all Individual and Junior Members of the IAU.

For the benefit of voters who were not present at the XXX General Assembly a document has been prepared by the Chair of the IAU Resolution Committee, Bruce Elmegreen and by the Former General Secretary Piero Benvenuti summarising the rationale behind Resolution B4 and the discussion that took place during the II Business Session of the General Assembly .

The IAU would like now to invite all Junior and Individual Members to vote on the adoption of Resolution B4 electronically, as indicated in the e-mails each member has received. To ensure neutrality, the electronic votes will be collected by an external provider. The voting will conclude on 26 October 2018 at 24:00 UTC, and the results will be available through the voting platform thereafter.

More information

The IAU is the international astronomical organisation that brings together more than 13 500 professional astronomers from more than 100 countries worldwide. Its mission is to promote and safeguard the science of astronomy in all its aspects through international cooperation. The IAU also serves as the internationally recognised authority for assigning designations to celestial bodies and the surface features on them. Founded in 1919, the IAU is the world's largest professional body for astronomers.


[1] The research paper Hubble published in 1929 was titled A Relation between Distance and Radial Velocity among Extra-Galactic Nebulae, and in 1931 it was followed by a paper written in collaboration with Milton Humason, which included additional observational data.

[2] This research was published in a paper titled Un Univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extra-galactiques, in French.

[3] In 1931, at the invitation of the journal Monthly Notices of the Royal Astronomical Society, Lemaître translated his paper from 1927. In it, he omitted the section with the derivation of the distance–velocity relation. Further information on this topic can be found in the article Mystery of the missing text solved by Mario Livio, published in the journal Nature.

[4] According to historical sources, Lemaître and Hubble both attended the III General Assembly of the IAU in 1928, where they exchanged ideas on the suspicion that observational data may show a correlation between the distance and radial velocity of extragalactic nebulae. A summary of the events that led to the dissemination of the observational confirmation of the expansion of the Universe can be found in the article Discovery of the Expansion of the Universe by Sidney van den Bergh, published in the Journal of the Royal Astronomical Society of Canada.



Piero Benvenuti
Former General Secretary, International Astronomical Union
Paris, France
Tel: +33 1 43 25 83 58

Madeleine Smith-Spanier
IAU Database Manager
Paris, France
Tel: +33 1 43 25 83 58

Lars Lindberg Christensen
IAU Press Officer
Garching bei München, Germany
Tel: +49 89 320 06 761
Cell: +49 173 38 72 621

About the Announcement



IAU Resolutions being presented at the GA 2018