There were a couple of nearby comets in 1910, but neither would have looked like more than a speck of light to the naked eye. So what's with this comet looking like a huge glowing sun in the sky and causing mass panic?
I guess I'm not quite getting the premise of the show. The Titanic episode was based entirely on fact, but this one seems to depict a fictional past. Is there supposed to be an alternate timeline/dimension in some stories?
It was Halley's Comet, which reached perihelion on April 20, 1910. It passed so close to Earth that the planet actually passed through its tail. This lead many people to panic after a French astronomer predicted that the gas from the tail would poison the atmosphere and kill everyone.
The view of the comet at the time was described as "spectacular", although TTT did crank it up a few notches. And, as far as I know, no one predicted an actual collision.
There's not supposed to be any alternative dimensions, etc., but if you've just started watching, you'll see that some of the later episodes get, shall we say, well beyond recorded history.
I see. Yep, I've just started the series.
There was also the Daylight Comet of 1910, which fits the story a bit better because it was seen in the middle of the day. It had such an impact that many people who remember seeing Halley's are actually remembering the Daylight Comet.