Boffin says Astronomical Unit should be binned Fails to allow
for shrinky sun, spiralling Earth 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. But Peter Noerdlinger of St Mary's
University points out  that in fact the Sun loses an ultra-
minuscule proportion of itself every second due to the continual
conversion of mass into solar energy. (About three millionths of
a quadrillionth goes every second if we've got our sums right;
or three billionths of a trillionth if you prefer. This equates
to around six million tonnes, which is 60 US Navy aircraft
carriers or 80-million-odd internation