It’s been a long, dreary winter. I am at dinner with a group of friends when someone wonders aloud when the first day of summer is. Lizzie insists it’s 21 June, Cleo is equally sure it’s 1 June. Sylvie says she is willing to bet her coveted The Row flip-flops on Cleo’s answer. The social rewards from “arguing” over this far outweigh knowing a trivial piece of information that no one at the table will remember. And yet, we can’t help ourselves.

Invariably, someone pulls out their phone, does a not-so-quick search online, and then declares, as though she has uncovered something truly revelatory, the first day of the astronomical summer is on the summer solstice, 21 June. Whereas 1 June is when the meteorological summer........

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