Is it possible to create a perfect sphere

The results were a big surprise. The sun doesn't bulge much at all. It is 1. Scaled to the size of a beachball, that difference is less than the width of a human hair. Only an artificial sphere of silicon that was created as a standard for weights is known to be more perfectly spherical. The results, reported in the journal Science , are the culmination of 50 years of efforts to precisely measure the sun, which have been hampered by the blurring effects of the Earth's atmosphere.

They used instruments on Nasa's Solar Dynamics Observatory , though these were not precise enough to make the observations directly. The definition of a kilogram way back in was the mass of one litre of water at four degrees Celsius. As of , the kilogram is defined by the mass of a platinum-iridium sphere, a physical artefact called the International Prototype Kilogram or IPK. The Avogadro Project, originating in Australia, has been trying to solve the kilogram problem for many years, with researchers at the Centre for Precision Optics crafting the spheres.

In the spheres, the number of atoms can be calculated using a laser to measure the diameter. Heason Technology has recently completed the design and supply of a UHV compatible and completely non-magnetic 5-axis manipulator. Commissioned by ITRI, it will be used to micro-position the silicon sphere that could play a significant role in the redefinition of the unit of mass for the International System of Units SI.

Over time, Heason have developed an in-house design and build service, curating a large portfolio of proven application successes for motion system installations in UHV for synchrotron sources and many other equally demanding research and manufacturing environments. The researchers calculate that it spins three times more slowly than our Sun, but is more than twice the size. In terms of exact measurements of 'roundness', they calculated that the difference between the equatorial and polar radii of the star is only 3 km - "a number that is astonishing small compared to the star's mean radius of 1.

To put those numbers into perspective, our Sun has a radius at the equator that is 10 km larger than at the poles, and for our lumpy old Earth, this difference is 21 km.

As Michael Byrne explains for Motherboard , asteroseismology is based on our ability to separate out the frequencies of acoustic waves emanating from a star's interior.

It's not clear what's causing this disconnect between the surface and core spin rates, but the researchers suggest that the presence of a magnetic field a low latitudes around the star could be the culprit.