The Wondrous calendar was introduced as a part of the Baha'i Faith in the 1800's but was finalized in 2014. It is a purely solar calendar that can be used by anyone and is easy to understand with just a few rules:
- Start the year on the vernal equinox.
- At the moment of the equinox, the current day (between sunsets) in Tehran, Iran is the first day of the year. Use astronomical tables to know this years in advance.
- Have 19 months of 19 days each.
- Leave a gap of 4 or 5 days before the last month, so that it ends the day before the equinox.
Some pages with more information: