The Rylixian Festival was an ancient tradition which was celebrated across the galaxies for millennia.
It was the one day of the cosmic year when planets across 482 recognised galaxies celebrate life itself. They celebrated the simple joy of living and love for their fellow beings — whatever planet they came from, however they might have looked. However, the festival took only one day; what happened the day after it was a different matter.
In 2009, Sarah Jane Smith, Alan Jackson, Luke Smith, Maria Jackson and Clyde Langer celebrated this day. They ate cake together and thanked each other for everything they brought into their lives and for always being there no matter what. Sarah Jane explained to Clyde and Luke that this day happened about once every generation in their time. (PROSE: The Last Sontaran)