showerRatefunction

How strong a shower is at a moment: its zenithal hourly rate then, 0 outside its dates. The list gives the rate at the maximum and the first and last days of activity; between them this draws the simplest curve that fits: the rate falls away from the maximum by the same factor for each degree the Earth moves on, down to half a meteor an hour at the start of the first day and the end of the last. A real shower's curve differs (the Quadrantids' maximum lasts hours, the Taurids' weeks). A shower the list calls variable gives 0.

import { showerRate } from "@johnmorrisdotca/chikyu-earth/meteors";

function showerRate(shower: MeteorShower, ms: number): number

import { METEOR_SHOWERS, showerRate } from "@johnmorrisdotca/chikyu-earth/meteors";

const geminids = METEOR_SHOWERS.find((shower) => shower.code === "GEM")!;
console.log(showerRate(geminids, Date.UTC(2026, 11, 14, 8)).toFixed(0), showerRate(geminids, Date.UTC(2026, 5, 1))); // "150" 0

132 0