Halley's Comet, as everyone knows, appears every 76 years - more or less. Its return in 1986 was a damp squib. We were all disappointed. But in 1910 its appearance had some interesting effects. Here is the brief account given by Frank Edward Johnson about what happened in Tripoli, in what is now Libya, on that occasion.
Rain water is the only drinking water used and is kept in huge cisterns build under the houses. During the passage of the Halley comet the Jews of Tripoli were afraid of dying and took refuge in their great cisterns, which they had pumped dry for the purpose. Twenty-four hours having elapsed, they came out of their hiding places to find the world the same as before.The Arabs said that they were in the hands of Allah and refused to take refuge in their cisterns. So the few foreigners and the Arabs were the only ones who had any drinking water left, and the Arabs sold drinking water to the Jews until the next rains, about six months later.
And if my experiences were anything to go on, the two groups would have lived in separate quarters of the city.
Reference: Frank Edward Johnson, 'Here and There in Northern Africa', The National Geographic Magazine, Jan. 1914, at pages 95-6