IAU Symposium 345:
Origins: From the Protosun
to the First Steps of Life

August 20 – 23, 2018



  • Yuri Aikawa (Japan)
  • Bruce Elmegreen (USA, co-chair)
  • Muriel Gargaud (France)
  • Manuel Guedel (Austria, co-chair)
  • Nader Haghighipour (USA, co-chair)
  • Lucyna Kedziora-Chudczer (Australia)
  • Susana Lizano (Mexico)
  • Morris Podolak (Israel)
  • Monica Rubio (Chile)
  • L. Viktor Tóth (Hungary, co-chair)

Scientific Rationale:

This symposium explores the chain of events that could have been involved in the formation of the Earth and the earliest lifeforms. Many steps in this process have been inferred already from detailed observations and computer models. Stars form in dense interstellar clouds and are usually clustered among other stars. The environment of the early Sun should have been affected by that clustering, as suggested by peculiarities in the isotopic composition of meteorites. Protoplanetary disks that may form Earth-size planets have been studied at high resolution using interferometric techniques in infrared and radio wavelengths. These observations reveal the chemistry and dust content of the disks, and possible interactions with the growing planets. While there are no direct observations yet of Earth-size protoplanets, there is evidence for Earth-sized planets around other stars, and there are clues to the formation process of the Earth itself from within our Solar System. The conditions for habitability are more difficult to observe and model. How these conditions arose and the nature of the first organisms are topics of intense study in many fields. The purpose of this symposium is to bring together researchers in these fields so that each component of our origins story can motivate and illuminate the others, while giving a concise summary of the current state of knowledge for the next generation. The approaching availability of large new observatories will provide an unprecedented opportunity to explore our origins even further.


  • The galactic environments of the Earth and Sun
  • Formation of solar-type stars and the Sun
  • Formation and evolution of protostellar disks
  • Physical and chemical conditions in the proto-solar nebula
  • Protoplanetary disks as factories of organics and volatiles
  • Planetary systems around solar-type stars
  • Toward building true Earth analogs
  • Interactions between the central star & atmospheres of Earth-like planets
  • Conditions on the early Earth, including geophysical processes
  • Steps toward habitability & early forms of life



Bruce Elmegreen

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