Meteor Shower Calendar

A meteor is a grain of dust, often no bigger than a grain of sand, hitting the air at 20 to 70 km a second. It burns up 100 km above the ground, and the trail of glowing air is what we see. Comets shed this dust as they pass near the Sun, and it spreads along their orbit into a stream. Where the Earth's orbit crosses a stream, it meets the dust on the same days every year: a meteor shower.

The grains of a stream all travel in parallel, so seen from the ground their trails all seem to come from one point of the sky, the radiant, the way parallel rails meet on the horizon. Showers are named after the constellation of their radiant: the Perseids come from Perseus, the Geminids from Gemini. The higher the radiant, the more meteors: with it on the horizon, the stream skims the air and few grains reach it. Meteors appear anywhere in the sky, though, not at the radiant, so there is no need to look straight at it.

The strength of a shower is given as its ZHR, the zenithal hourly rate: the meteors one person would see in an hour under a perfectly dark sky, with the radiant overhead. Real skies are never that good, so the counts here are corrected for the height of the radiant, the darkness of the sky you pick, and the Moon. Moonlight washes out the faint meteors, which are most of them: a full moon can take away three quarters of a shower. A few days either side of new moon are best.

Most showers are better after midnight. In the evening we are on the trailing side of the Earth, and only meteors catching up with us hit the air; after midnight we face forward in the Earth's orbit, into the dust, like a windshield in the rain. The radiant is also higher then, for most showers.

To watch: get away from lights, lie back on a reclining chair or a blanket, and give your eyes 20 minutes to get used to the dark (no phone screens, or a red light). Look up and a little away from the radiant, at the darkest part of the sky, and be patient: meteors come in bunches, with long quiet gaps between them. No telescope or binoculars, they show too little of the sky.

The peaks, rates and radiants are those of the International Meteor Organization's calendar; the dates of the peaks are computed in your browser from the solar longitude, the point of the Earth's orbit where each shower peaks, and the positions of the Sun and the Moon with the methods of Jean Meeus's Astronomical Algorithms. Real showers vary from year to year, and some, like the Draconids or the Leonids, can surprise with an outburst: the rates here are a guide, not a promise.