The 13-month Sol Calendar is a proposal for calendar reform by Jim Eikner of Austin, Texas, USA, providing for a year of 13 months in length, with 12 contiguous months having 28 days each, with the final month of the year, December, having 29. December would have 30 days in leap years. The months are named the same as they are in the Gregorian calendar, except that a month called Sol is inserted between June and July. * * December 29. * † In leap years December 30 is added. The next leap year beginning on Sunday would be 2012. The 13 months occur on the following Gregorian dates: