 Why did the aliens decide to land during wintertime?
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. A meteor shower could pass over and their clumsy instruments could interpret it as an all-out enemy attack." There's nothing in this region of space our people want," said Ethaniel. "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."
 They had to land now, and went where they could identify the best people to talk to.
 They did not have enough gas to circle back in the summer time.  They preferred the cold in the northern hemisphere to the heat of the southern hemisphere.  They had to land now, and went where they could identify the best people to talk to.  Their clothing fit in better in colder climates.