According to Nathan Fillion, the main actor in Firefly, the holiday is on September 20th.
The Church of Jesus Christ of Latter-day Saints | Green Day | One Day International | New Year's Day | Boxing Day | Memorial Day | Seventh-day Adventist Church | Labor Day | Doris Day | Earth Day | May Day | Sandra Day O'Connor | Valentine's Day | Record Store Day | Mother's Day | Ferris Bueller's Day Off | Bastille Day | Six-Day War | April Fools' Day | Australia Day | Father's Day | Brightest Day | Big Day Out | Unification Church | Macy's Thanksgiving Day Parade | Canada Day | Victory in Europe Day | Long Day's Journey into Night | Armistice Day | The Day After Tomorrow |
He joined the Unification Day Cup dragon boat races on the occasion of the German Unity Day dragon boat races.
"Great Union Day" on December 1, also known as "Unification Day", the national holiday of Romania