For some, it was a time to celebrate. For others, it was a time to hide -- and perhaps even the end of time for life on Earth.
It was May of 1910, and Halley's Comet was passing through the inner solar system. It had zipped closest to the Sun a few weeks before, and was now swinging past Earth. In fact, it was so close that Earth was flying through the comet's long, wispy tail.
And that's where the trouble started.
Like all comets, Halley is a big ball of frozen water and other ices mixed with solid bits of rock and dust. As it approaches the Sun, some of the ice vaporizes and spews into space. The Sun pushes some of this material away from the body of the comet, forming the tail.
Before Halley's closest approach to Earth, astronomers at Yerkes Observatory discovered traces of a deadly compound known as cyanogen in the comet's tail. French astronomer Camille Flammarion was concerned that the gas would infiltrate Earth's atmosphere and kill off most living organisms.
Other astronomers pointed out that Halley's tail was so diffuse that there was no threat at all. Just in case, though, many people bought "comet pills" and other bogus protections. Some hid in caves, or sealed their homes against the outside air.
But many others just enjoyed the show. They staged rooftop "comet parties," and watched Halley as it passed harmlessly by -- not to return for another 76 years. We'll have more about that next appearance tomorrow.
Script by Damond Benningfield, Copyright 2010