Astronomical unit
= Astronomical unit
{title2=$\mathrm{AU}$}
The astronomical unit is a length scale used for Solar System distances, approximately $1.5\times10^{13}\,\mathrm{cm}$. Coarse estimates sometimes round it to $10^{13}\,\mathrm{cm}$. Numerical coefficients in <planet formation> estimates depend on which approximation is used.