Ismail Bouillaud then estimated its period at 333 days, less than one day off the modern value of 332 days, and perfectly forgivable, as Mira is known to vary slightly in period, and may even be slowly changing over time.
Leta 1638 je Johannes Holwarda izmeril periodo Mirinih pojavljanj, enajst mesecev; pogosto zasluge za odkritje Mirine spremenljivosti pripisujejo njemu.