 What is the connection between the aliens in the present holiday?
A gentle fancy for the Christmas Season—an oft-told tale with a wistful twistful of Something that left the Earth with a wing and a prayer. Earth was so far away that it wasn't visible. But this vast distance did not mean that isolation could endure forever. Instruments within the ship intercepted radio broadcasts and, within the hour, early TV signals. The history of the planet was tabulated as facts became available. "It's not what they've done," said Bal, the second alien. They've had two world wars in one generation and that the third and final one is coming up you can't help feeling in everything they do." "The wrong diplomatic move, or a trigger-happy soldier could set it off. A meteor shower could pass over and their clumsy instruments could interpret it as an all-out enemy attack." "It is. "There is. "In a week we can't negate their entire history. "And when we get to Willafours we'll be busy. "And how long can Earth last? They went much closer to Earth, not intending to commit themselves. For a day they circled the planet, avoiding radar detection, which for them was not difficult, testing, and sampling. Atmospheric analysis showed that as far away as we were." "What's worse is that I now find they also have missiles, range one thousand miles and upward. They either have or are near a primitive form of space travel."
 The aliens happen to fit the image many humans have of this holiday.
 The holiday allows the aliens to study the economic impact of holidays.  The timing of this trip allows the aliens to see an important holiday first hand.  The aliens happen to fit the image many humans have of this holiday.  The holiday means that there are more people off of work to interact with for the aliens to learn from.