The new feature for in this version of the orrery is
the ability to display comet information.   Two
potentially bright comets, named Pan-STARRS and
ISON,will pass through the inner solar system in
2013.   Their ephemerides have been included in
this package.   Information about them can be
displayed for one year before and after their next
perihelion passage.
 
The Default Sky, Planet Compass, Planet Elevations
To-Scale Solar Sys and new Comets page can all show
information about the comets during the period
covered by the ephemerides.   Outside of that period,
information about the comets is not displayed
anywhere.   The Displayed Items menu item allows you
to enable or disable the presentation of the comet
information.

As usual, all this stuff is discussed ad nausium on
the orrery wiki page.
