This will be a brief foray into the intricacies of the least
understood atmospheric layer:the mesosphere. I will discuss the
structure and important features of this highly dynamic region, the
history of mesospheric measurements, and how remote sensing is used to
retrieve the state of the mesosphere. More recent advances in the
understanding of this under-sampled region will also be discussed, with
highlights of ongoing observations from the Canadian OSIRIS instrument
on the Odin satellite.