PerspectivePlanetary Science

Probing the solar system's prenatal history

Science  08 Aug 2014:
Vol. 345, Issue 6197, pp. 620-621
DOI: 10.1126/science.1257083

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Summary

Stars like our Sun are formed by the gravitational collapse of the densest parts of molecular clouds comprising dust and gas. Collapsing clouds swiftly evolve to form young stars surrounded by disks from which planets originate. The time scales and processes leading to the formation of our own solar system will be important clues to the birth environment of other planetary systems orbiting Sun-like stars, which may exist in greater numbers than previously thought (1). Radiometric age dating of meteoritic inclusions has established that the birth of our solar system occurred 4567.3 ± 0.16 million years ago (2). But there is also life before birth. This distant, recordable past reflects the time when the matter from which the solar system formed became isolated from the chemically evolving interstellar medium. By analogy with a human life, this epoch represents the embryonic and fetal stages of gestation. On page 650 of this issue, Lugaro et al. (3) report that the precursor material to the solar system may have been isolated from the galaxy as early as 30 million years before its birth. Considering that it took less than 100 million years for the terrestrial planets to form, this incubation time seems astonishingly long.