Solar sweep

A solar sweep, often shortened to simply sweep, is the unit of time it takes for Alternia to complete one full orbit around Sol. Despite its localised nature, it is a standardised unit throughout the Alternian Empire.

Many perigees and apogees occur during one sweep.

Sweeply events
Many events, such as holidays, are sweeply, meaning that they take place just once per sweep, every sweep.
 * One day before the 12th perigee - 12th Perigee's Eve