Boffin says Astronomical Unit should be binned

[Rick]

An astronomer based in Canada has published a paper arguing that distances within the solar system should no longer be measured using Astronomical Units (AU), which is currently standard practice.

An AU is approximately equal to the distance between Earth and Sun, but the International Astronomical Union actually defines it differently. According to the IAU, an AU's value is based on the Gaussian gravitational constant - which itself assumes that the Sun has a constant mass.

More: http://www.theregister.co.uk/2008/02/07/astronomical_unit_inaccurate_shrinking_sun/