  We present a numerical code to simulate maps of Galactic emission in
intensity and polarization at microwave frequencies, aiding in the design of
Cosmic Microwave Background experiments. This Python code builds on existing
efforts to simulate the sky by providing an easy-to-use interface and is based
on publicly available data from the WMAP and Planck satellite missions. We
simulate synchrotron, thermal dust, free-free, and anomalous microwave emission
over the whole sky, in addition to the Cosmic Microwave Background, and include
a set of alternative prescriptions for the frequency dependence of each
component that are consistent with current data. We also present a prescription
for adding small-scale realizations of these components at resolutions greater
than current all-sky measurements. The code is available at
https://github.com/bthorne93/PySM_public.
