24 Oct
2017
24 Oct
'17
11:56 a.m.
I don't understand that. The celestial sphere is defined as not rotating and is empirically fixed by distant galaxies. Brent On 10/23/2017 9:06 PM, Keith F. Lynch wrote:
(Copernicus, Galileo, Kepler et al believed that the celestial sphere stood still and Earth rotated. They were mostly right, but if they had kept close track, they would have noticed that the celestial sphere rotates by about 0.04 seconds of arc per year due to frame dragging.)