Nov 17 1999
From The Space Library
NASA announced that new analysis of data from the Galileo spacecraft suggested that Jupiter is possibly much older and colder than previously thought. Upon reaching the planet on 7 December 1995, Galileo had dropped a probe carrying a mass spectrometer into Jupiter's atmosphere to measure its chemical composition. The spectrometer had "detected surprisingly high concentrations of argon, krypton, and xenon," raising questions about the noble gases' provenance. Because Jupiter would have trapped the gases through condensation or freezing, scientists did not believe Jupiter's atmosphere had trapped the gases at its present site. As positioned at present, Jupiter is too close to the Sun and too warm to have trapped the gases. Tobias Owen, an astronomy professor at the Institute for Astronomy of the University of Hawaii and a member of the Galileo probe Neutral Mass Spectrometer team, suggested three hypotheses to explain how the gases had been trapped within the Jovian atmosphere: 1) Jupiter had formed in the area around the Kuiper Belt829 and was dragged inward to its present location; 2) the solar nebula, the cloud of gas and dust that formed the solar system, had been much colder than scientists had previously believed; and 3) the solid materials that had brought the gases to Jupiter had begun to form in the original interstellar cloud of gas and dust, before the cloud had collapsed to form the solar nebula. Owen remarked further that, if either of the last two hypotheses were correct, then giant planets might be able to form closer to their stars than current theories had predicted. Such a finding could help explain "the new observations of planetary systems around other stars, in which such close-in giant planets are relatively common."
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