Volunteers Use Annular Eclipse To Measure Sun More Accurately

Anonymous Squonk writes "The measurement of the sun currently in use was actually calculated over 120 years ago, and is off by hundreds of kilometers. Thousands of ordinary Japanese citizens worked together to improve this estimate. By measuring the borders of the 'ring of fire' effect of the recent eclipse, and using the known size and distance from the Earth of the sun, the radius of the Sun was measured as 696,010 kilometers, with a margin of error of only 20 kilometers."

Incidentally...

[fuzzyfuzzyfungus]

I very strongly doubt that this is relevant on the scale of recorded human history and naked-eye observation; but doing all that mass-energy conversion and indiscriminate radiating must be slowly changing the sun's size, with some sort of balance between loss of mass and thermal expansion or contraction.

I'm told that the 'expands and engulfs the inner planets' stage will be dramatic; but is the expectation before that event a very, very gradual shrinking or something more complex?

Re:Incidentally...

[SuricouRaven]

Don't forget the cycle too. Sunspots go up, sunspots go down.. that means a change in temperature, and as basically a ball of gas a change in temperature means a change in volume. I don't know how significent this pulsing effect would be, but if you can do measurements to 20km it might be measurable.

Define 'Sun'

[EasyTarget]

Seriously; it has a atmosphere thousands of miles thick, with a fuzzy, boiling edge..

The margin of error on this is ludicrous.

Plus.. of course, it is continually boiling itself off onto space, so even if you could define a 'hard edge' to it, your measurements would become worthless in, say, a few million years ;-)