A study by John Eddy and Aran Boornazian, based on historical naked-eye observations of the Sun, reported that these observations indicated the Sun was shrinking at a rate of five feet per hour. This study was never published in a referreed academic journal, but it was mentioned in a couple of physics and astronomy magazines. In response to the study, a paper was quickly published in a referreed journal which used measurements of the size of the Sun based on telescopic observations of the passage of the planet Mercury across the Sun's face, which are much more accurate than naked-eye observations, to demonstrate clearly that the Sun is not shrinking as fast as suggested by the original study, and may not be shrinking at all. This result was also published in Sky and Telescope . Further, There is no reason to expect that even if the Sun is currently shrinking that it has always been shrinking, and at the same rate, which is exactly the assumption that must be made to conclude that the Sun would have been larger than the Earth's orbit millions of years ago.
More recent studies show that the Sun expands and shrinks in an eighty-year cycle.
In fact, the author of the original study points out that even when they thought they shrinkage was real, they didn't think it involved the entire Sun, only its outer layers, and that they expected the shrinkage to be part of an oscillatory phenomenon. Back to the Rules page.