How important was Halley's comet to science

To this day, the sudden appearance of the tail stars in the sky has raised concerns among part of the population. Comets used to be a sign of angry deities and heralded seemingly terrible hardships such as epidemics or wars. In the modern age, when it was already known what comets are, there were more concrete ideas of their possible dangers. The probability of an impact is very small, but not zero and caused serious concerns more than a hundred years ago (see picture below). Should this unlikely event ever occur, the consequences, depending on the size of the comet's nucleus, would be catastrophic and could have global repercussions.

It was not until 1705 that the British astronomer Edmond Halley realized that a certain comet appears to return every 76 years and that many of the phenomena that have been recorded over centuries can be traced back to it. He predicted the return of this comet for the year 1759, but it was not granted to him to experience its triumph because he died in 1741, 18 years earlier. The comet was named after him in Halley's honor.

Halley's Comet was thus the first to be recognized as periodic. At least some of the tail stars - which were perceived as phenomena within the earth's atmosphere until well into the 16th century - had to move on elliptical orbits around the sun, which made them permanent members of our solar system.

With advances in physics and astronomy, knowledge of the properties and chemical composition of comets also grew. The latter worried people: shortly before Halley's Comet came closest to Earth in 1910, astronomers had used the then still young spectral analysis to recognize that the gas tail contained hydrogen cyanide. In fact, they were on the positively charged cyanide radical CN+encountered. And worse, the orbital calculations predicted that the earth would even pass through the comet's tail on May 19, 1910.

Was humanity threatened with poisoning? Would a massive prussic acid death set in in the country and in the cities, which we knew would be short, but extremely painful? Or did you get away with just nausea and the hum of your skull?

It was easy to calculate that in some highly valued schnapps there was a concentration of hydrocyanic acid that was a factor higher than in Halley's tail. Regardless of this, the sellers of "comet pills" for poisoning prophylaxis made bombastic deals. Gas masks and other "protective equipment" were also very popular. Although there was thoroughly serious reporting and easily understandable popular science treatises (see the two pictures on this double page), the "comet panic" was able to spread astonishingly far. When, of course, nothing happened at all, others had the laugh and good jobs: the cartoonists.

Tilmann Althaus, Axel M. Quetz

Even in our modern times, fear of heaven plays a role. The article in Sterne und Weltraum 5/2010, pp. 72-75, shows some of the works of the cartoonists mentioned and describes threats from space that have been implemented on film: www.astronomie-heute.de/1029149.