Slashdot Mirror
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."
The Sun is growing right now and it is getting brighter by the day. This is not occurring at a rapid rate at the present time. It is due to the slow accumulation of helium in the core of the Sun. Helium doesn't undergo fusion at this time (not hot enough). The increase in helium would imply a decrease in the fusion rate, but due to maintaining a hydrostatic equilibrium, the temperature of the core increases and the fusion rate actually increases. This causes the radius to increase.
To be more precise, the sun will become a red giant in about 5 billions, engulf the earth, and eventually fade as a white dwarf, whose volume is about the same as the earth.