The Sun has neither of these (the centrifugal acceleration at the equator is only about 20 millionths of the surface gravity, and Jupiter is too small and far away to have an effect) and simply relaxes to an almost spherically symmetric configuration. ![]() Possible sources of asymmetry in stars could include rapid rotation or the presence of a binary companion, both of which break the symmetry of the effective gravitational potential, even if the star were spherically symmetric. The resultant pressure gradient would trigger fluid flows that would erase the asymmetry. Any departure from symmetry would imply a difference in pressure in regions at a similar radius but different polar or azimuthal angles. The Sun has had plenty of time to reach an equilibrium between its self gravity and its internal pressure gradient. ![]() The symmetry of the Sun has got very little to do with any symmetry in its formation. Can anyone explain from what causes this symmetry emerged? Is it a combination of a slow rotation rate combined with a highly isotropic central gravitational field? I thought there would be an equatorial bulge, even though the rotation rate is slow.ĭoes this result, for just one ordinary, as far as I know, star indicate that asymmetrical stellar collapses are much less likely than may have been previously envisaged? Admitted, it is just one star out of countless billions, but on the other hand, as it is a random sample, it may well be indicative of many more similar "extremely" (if I can use that word) spherical objects. To me at least, it is a completely counter-intuitive result. However, Wikipedia accepts its validity:īy this measure, the Sun is a near-perfect sphere with an oblateness estimated at about 9 millionths, which means that its polar diameter differs from its equatorial diameter by only 10 kilometres (6.2 mi). I do appreciate that above result is just one measurement, and I looked for confirmation of the result. ![]() If scaled to the size of a beach ball, it would be so round that the difference between the widest and narrow diameters would be much less than the width of a human hair. Relatively recent measurements indicate that the Sun is nearly the roundest object ever measured.
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