Through an Hourglass Darkly

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Science  16 Jul 1999:
Vol. 285, Issue 5426, pp. 350-351
DOI: 10.1126/science.285.5426.350

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The radioactive isotopeAl is one of the key elements for astronomers and planetary scientists wishing to understand star formation in our galaxy and the early history of our solar system. In the galaxy, the gamma-ray flux emitted by decayingAl provide a measure of its abundance. Its half-life is too short for anyAl present at the beginning of the solar system to still be alive there, but its daughter element,Mg, can be measured in meteorites. Meyer discusses the difficulties in interpreting inferredAl abundances in the early solar system, and describes recent studies investigating two models, the heterogeneous and the homogeneous distribution model forAl in the early solar system.