Abstract
THE PRESENT CONDITION or THE GIANT PLANETS.—Some surprise was created at the meeting of the Royal Astronomical Society on April 13 by a paper from Dr. Harold Jeffreys in which he raised doubts about the generally accepted view that these planets are still at a very high temperature. He made an estimate of the amount of heat that would have been radiated by Jupiter in the course of a period of three hundred million years, on the assumption of a high temperature throughout this period, finding that it exceeded the probable initial supply; he drew a further argument from the low densities both of primaries and satellites, in the case of these four planets, concluding that they are built of less dense materials than the inner planets. While there was some agreement with these views at the meeting, there were several expressions of dissent. The very energetic processes that are obviously going on upon Jupiter can scarcely be ascribed to the very feeble solar radiation, which is only one-twenty-seventh of that received by the earth. Moreover, if Jupiter were formed of material of the same density as that forming its satellites, the much greater force of gravitation upon it would produce a higher density through compression, unless counteracted by heat or some similar agency. A further argument was drawn from the spectra of these planets photographed at Flagstaff; these all showed broad absorption bands, implying dense atmospheres.
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Our Astronomical Column. Nature 111, 615 (1923). https://doi.org/10.1038/111615a0
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DOI: https://doi.org/10.1038/111615a0