It's easy to lose track of time when you're consistently flying through the darkness of space and encountering different climates. Fortunately, the Serenity crew kept their logs up to date. And even if they somehow were to miss a day, they had a Shepherd to remind them of the holidays.
"I suspect you realize what time of year it is," Shepard Book said to Malcom Reynolds one afternoon as the two ate in the kitchen.
"Of course I do," Mal said, "It's only a few more weeks until the end of the year,"
"That it is," Book said, "Which means it's almost Christmas,"
Mal took a swig of his drink. "We don't celebrate holidays on this ship," he said matter-of-factly.
"Really?" Book asked. "Not a single holiday?"
"What one chooses to celebrate in their own quarters is up to them," Mal said. "But collectively, we have business to conduct,"
"Some would argue that there are things more important than business transactions," Book said. "From both a spiritual and social standpoint,"
"We haven't celebrated any holidays on this ship before," Mal repeated, his tone a bit sharper than he'd intended, "So why would we celebrate Christmas now?"
"Are we celebrating Christmas this year?" Kaylee asked excitedly as she walked into the kitchen.
Before Mal could reply Book asked her "Would you be interested in doing so?"
"Of course!" Kaylee replied enthusiastically. "I haven't celebrated properly since I was with my family on my home planet," Kaylee's eyes lit up. "It could be even more meaningful now that we have a Shepherd on board!"
"Then I believe we can arrange something small on the 25th," Book said.
"Why does it have to be small?" Kaylee said. "It's Christmas after all," Kaylee gazed at Mal, who looked as though he regretted ever setting foot into the kitchen. "Is it because of Mr. Grumpy Pants over here?" she asked.
"We have schedules to attend to," Mal said, his excuse sounding pathetic even to his own ears.
"Oh come on, don't be such a Scrooge," Kaylee teased. "Once I tell the others about the plan, we'll make it the best Christmas Serenity has ever seen!"
"No, we're not telling the others," Mal said, but Kaylee was already out the door.