How to watch a meteor shower

On any clear night, several meteors an hour can usually be seen; during a meteor shower there are many more.^[1] Showers are predictable, returning at the same time each year, and watching one needs no equipment at all: a dark place, time for your eyes to adjust, and patience.

What a meteor shower is

Comets, and in a few cases asteroids, leave trails of dusty debris along their orbits. When Earth passes through one of those trails each year, the debris enters the atmosphere and burns up as meteors.^[1] Most of the particles are between the size of a grain of sand and a pea, and they burn up long before reaching the ground.^[1] Each shower has a parent body: every Perseid meteor, for example, is a tiny piece of comet 109P/Swift-Tuttle.^[2]

The radiant

The meteors of one shower travel on nearly parallel paths, so they appear to spread out from a single point in the sky, the radiant.^[3] A shower is named after the constellation where its radiant lies: the Perseids appear to come from Perseus.^[2] The constellation is only a guide for telling showers apart; it is not the source of the meteors, and meteors can appear anywhere in the sky.^[2][4] There is no need to stare at the radiant.

What the ZHR means

Shower forecasts give a zenithal hourly rate, or ZHR: the number of meteors one observer would see in an hour if the radiant were directly overhead and the sky dark enough to show stars of magnitude 6.5.^[3] Real conditions are almost always worse. A radiant lower in the sky, haze, city lights or moonlight all reduce the count, so the number of meteors you see is usually well below the ZHR.^[3] NASA expects 50 to 100 Perseids an hour at the peak under good conditions, for example, and about 15 an hour from April's Lyrids.^[4][5]

How to see the most meteors

• Pick the right night and time. Rates are highest around the shower's peak. Most showers are best after midnight, in the hours before dawn.^[5]
• Get away from lights. City lights and a bright Moon hide the fainter meteors; find the darkest sky you can, with a clear view of as much of the sky as possible.^[5] If a bright Moon is up during a peak, NASA advises watching in the hours before dawn, after the Moon has set.^[6]
• Let your eyes adjust. Give your eyes 20 to 30 minutes in the dark, and do not look at a phone or other light, which undoes the adjustment; a red light preserves night vision.^[4][5]
• Lie back and look up. Use a reclining chair or ground pad, relax your gaze and take in as much of the sky as you can.^[5]
• Leave the telescope at home. Binoculars and telescopes show only a small patch of sky, which lowers the chance of catching a meteor.^[5]
• Stay at least half an hour. Meteors arrive unevenly, with bursts and quiet spells, so watch for at least 30 minutes; the International Meteor Organization asks observers who count meteors to watch for at least an hour.^[5][7]
• Dress for the night. Overnight temperatures can be cold; bring warm clothing and a blanket.^[5]

Checking your sky

The faintest star you can see, your limiting magnitude, tells you how good your sky is. If the faintest stars you can see are magnitude 3, a meteor shower may not be worth the wait; at magnitude 5, meteors and the Milky Way should be visible.^[8] The Moon's phase matters as much as the location; see The Moon. Unusually bright meteors are covered in Fireballs and meteorites.