  We used infrared data from the Lunar Reconnaissance Orbiter (LRO) Diviner
Lunar Radiometer Experiment to globally map thermophysical properties of the
Moon's regolith fines layer. Thermal conductivity varies from
7.4$\times$10$^{-4}$ W m$^{-1}$ K$^{-1}$ at the surface, to
3.4$\times$10$^{-3}$ W m$^{-1}$ K$^{-1}$ at depths of $\sim$1 m, given density
values of 1100 kg m$^{-3}$ at the surface, to 1800 kg m$^{-3}$ at 1-m depth. On
average, the scale height of these profiles is $\sim$7 cm, corresponding to a
thermal inertia of 55 $\pm$2 J m$^{-2}$ K$^{-1}$ s$^{-1/2}$ at 273 K, relevant
to the diurnally active near-surface layer, $\sim$4-7 cm. The
temperature-dependence of thermal conductivity and heat capacity leads to a
$\sim$2$\times$ diurnal variation in thermal inertia at the equator. On global
scales, the regolith fines are remarkably uniform, implying rapid
homogenization by impact gardening of this layer on timescales $<$ 1 Gyr.
Regional and local scale variations show prominent impact features $<$ 1 Gyr
old, including higher thermal inertia ($>$ 100 J m$^{-2}$ K$^{-1}$ s$^{-1/2}$)
in the interiors and ejecta of Copernican-aged impact craters, and lower
thermal inertia ($<$ 50 J m$^{-2}$ K$^{-1}$ s$^{-1/2}$) within the lunar cold
spots identified by Bandfield et al. (2014). Observed trends in ejecta thermal
inertia provide a potential tool for age-dating craters of previously unknown
age, complementary to the approach suggested by Ghent et al. (2014). Several
anomalous regions are identified in the global 128 pixels-per-degree maps
presented here, including a high-thermal inertia deposit near the antipode of
Tycho crater.
