The Sun is Just 0.0007% Away From Being a Perfect Sphere

The Sun is the most perfectly round natural object known in the universe

The gas outflows of a coronal mass ejection, copied and pasted, turn this satellite image of the Sun into a beautiful flower. Photo: NASA SDO

Trying to draw a circle is really hard. You’re normally better off overturning a cup or bottle cap or finding something else to trace. It turns out, though, that the best tracing tool you could find has been hanging overhead all your life.

“The Sun,” says the Guardian, “is the most perfectly round natural object known in the universe.”

The Sun was long thought to be a little bit squat, being fatter at the equator than elsewhere. That is, until Jeffrey Kuhn and others published their study. The Guardian:

The sun doesn’t bulge much at all. It is 1.4m kilometres across, but the difference between its diameter at the equator and between the poles is only 10 kilometres.

Further, despite the fact the Sun goes through a regular changing in activity, which correlates to increases in solar flares and other solar events, they found that the star’s shape doesn’t budge. The award for the most perfectly round sphere in existence, though, probably goes to electrons. Or to Achim Leistner’s glass spheres.

By contrast, the blue sphere of the Earth isn’t round at all. As New Scientist points out, the Earth is sort of shaped like a potato.


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