An Air Force contractor will be launching an unmanned NASA lunar spacecraft from the Wallops facility in eastern Virginia.
Launch window is between 11:27 and 11:31 pm. The rocket should be visible in the D.C. area within a minute after launch. It will remain visible for perhaps a minute. Look to the ESE. Skies should be clear tomorrow night.
More details available at the Orbital website:
-Andy Sovonick of Gaithersburg