The sun is round. Very, very, very round.

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The sun is the roundest natural object known to humans, according to new research. University of Hawaii researcher Jeffrey Kuhn and his colleagues used NASA's space-based Solar Dynamics Observatory to precisely measure the sun's shape. A precise understanding of the sun's roundness and the factors that shift its shape, such as sub-surface turbulence, could shed new light on changes in the Earth's climate. From National Geographic:

If the sun were a meter-wide (3.3-foot-wide) beach ball, Kuhn said, the variation in the sun's shape from the highest to the lowest point would be about 17 microns—less than the width of a fine human hair, according to the SDO measurements…

Study leader Kuhn said his team is going to update computer models of the sun's cycle to see if and how the highly accurate shape affects their behavior.

"We're not done with measurements, though. We need to follow a full 11-year solar cycle to make sure the sun isn't fooling us," Kuhn said. "By doing that we can improve the accuracy even further."

"Sun Is Roundest Natural Object Known"


  1. Is it by any chance the roundest object known to humans full stop?  That is to say, are there any non-natural objects which are rounder?  It is hard to imagine an ordinary manufacturing process resulting in something that round, but maybe it is possible using magnets and lasers and liquid helium and shit.

    1. To answer your question I think the roundest object know to humans full stop is actually a full stop. I may be wrong though…

    2. No it’s not the roundest object known to humans since we have made rounder objects. The Gravity Probe B gyroscopes were round down to 40 atoms which is less than 10 nanometers. If they were a 3.3 foot wide sphere (rather than the size of a ping pong) the variation would be <250 nanometers. They have been since then surpassed by even rounder objects I believe. I am not sure how they were made.

      For reference, 17 microns is 17,000 nanometers

  2. What about George Michael’s butt? “It’s a perfect circle! English scientists use it to calibrate their instruments! Accept it before it destroys you!”

  3. That is interesting…  My understanding was that a neutron star has the highest sphericity of any known object.  And there are man-made objects that are almost as round, like the spheres from Gravity Probe B that I photographed here:

    1. *In theory* a neutron star *should* have the highest sphericity of any known object, but none of them are close enough to be measured as an actual known object.

      I don’t know whether it’s possible for a neutron star to be spinning fast enough to bulge significantly around the middle against its own gravity. I’m going to guess no, but again, no real data.

      Black holes might have a nonzero radius. If they do, they should be rounder than neutron stars.

      Going the other way… is a neutrino a known object? Would it even make sense to say that it has a shape, and that since it doesn’t really interact with anything much, the shape is probably undistorted by neighbouring fields and so completely symmetrical i.e. spherical. As far as we know, neutrinos aren’t made of bits of anything smaller, so why not imagine them as perfectly spherical wave/particle/field thingies?

      1. Black holes always seem to be imaged on TV as a bottomless pocket in the center of a two-dimensional pool table, but i realize that can’t be.
        Also unknown is what gravitational turbulence (if any) might roil around the event horizon.
        Some physics experts should get together with some 3-D graphics wizards and work on it.

        1. Stephen Hawking’s Into the Universe has an episode about black holes and their effect on time. There was a part about a ship orbiting one from a distance to slow aging and effectively time travel to the future. 

      2.  Well, the singularity in the black hole is a point (as far as we know mathematically) So it doesn’t take up any volume.

        The schwartzchild radius of a black hole is also a mathematical solution to an idealized circumstance: a spherically symmetrical, non rotating black hole.  So that’s not necessarily “real” either, and isn’t a surface to boot.

        A spinning black hole, (which almost certainly all of them are) has an ellipsoidal ergosphere.

        I suspect that a slowed down neutron star would be a viable candidate for most spherical object in the universe.

        1. Hmm. Modelling a black hole mathematically as a point, we get a singularity with all the divide-by-zero and infinite values that go with that. But the singularity is only *known* to be present in the mathematical model: we don’t know whether real life can even have singularities.

          Maybe nothing can be smaller than the Planck length? Maybe there’s an absolute upper limit on spacetime curvature we don’t know about? I kind of wish the large hadron collider had made a little black hole or two to give us a bit more data, but it was never very likely :(

  4. I don’t see why this is surprising.  It’s effectively a liquid, with one hell of a lot of self-gravity and any other forces acting on it are tiny.  But there really should be a footnote: round except for all those plumes and splashes and giant ring things.

  5. Actually this statement that the Sun is the roundest known natural object is false. The electron is much rounder than the Sun. This article says that if the Sun was scaled down to a meter in size it would deviate from being a perfect sphere by less than the width of a human hair. However, if an electron were to be scaled up to the size of the solar system, it would deviate by about the same width.

    1. Troll much? I think you know full well that the electron has no discernible size. It’s a point particle and thus the notion of “scaling it up” makes no sense at all.

  6. You can safely look at the sun with an old school welding helmet  using a minimum lens Shade #9. Auto-darkening no so good. Alternately, use acetylene glasses , shade #5, too view detailed sky/clouds with an emerald tint. It’s like looking at Oz. 

    So much is talked about climate change. It has been going on for years. Back when the glaciers where retreating form the equator. The few nomads feared using of the fire as they thought, it was melting the glaciers. But the Old Order told them to be sure, it is the sun that festers, not our fires, and melts the glacier belts. Ice vanished. Retreat of the massive glaciers as the Sun woke up and shone it’s mighty light. Carving its length back to the poles. As a pulsar fluctuating of contraction and expansion. A breath of time. Sat Nam said the people. Ra, said the Gods.

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