What a meteor shower is
Comets, and a few asteroids, shed dust as they orbit the Sun. Over centuries that dust spreads along the orbit into a stream. When Earth passes through a stream at the same time each year, the grains hit our atmosphere at speeds of roughly 20 to 70 kilometers per second and burn up 70 to 120 kilometers overhead. Most are smaller than a grain of sand.
Because the grains travel in parallel, their trails seem to spread out from a single point in the sky, the radiant, in the same way parallel railway tracks seem to meet in the distance. Showers are named after the constellation that holds their radiant: the Perseids from Perseus, the Geminids from Gemini.
Pick the right night
Every shower has a peak, when Earth passes through the densest part of the stream. Some peaks are broad: the Perseids give good rates for several nights either side of their maximum. Others, like the Quadrantids, are sharp, with the best rates lasting only a few hours, so the time of the peak decides whether your part of the world gets a good show.
The Moon matters as much as the date. A bright Moon washes out the fainter meteors, which are the majority. If the peak falls near full Moon, the nights a few days before, when the Moon rises later, can be better. Check the Moon phase calendar and each shower’s page on Meteor showers for dates and timing.
Pick the right hour
For most showers, the hours after midnight are best. Two things happen. First, the radiant climbs higher, and the higher it is, the more meteors reach your part of the atmosphere. Second, after midnight you’re on the side of Earth that faces forward in our orbit, so you run into more debris, like a windshield collecting raindrops.
The Geminids are the friendly exception: their radiant is already well up by mid-evening, so they are one of the few showers worth watching before bedtime.
What ZHR really means
Shower forecasts quote a zenithal hourly rate, or ZHR: the number of meteors one observer would see in an hour with the radiant directly overhead and a sky dark enough to show stars of magnitude 6.5. It’s a standard for comparing showers, not a promise.
Real rates are almost always lower. With the radiant halfway up the sky you lose about 30 percent. From a suburb, where only stars to magnitude 5 are visible, you might see a third of what a dark-site observer sees. A shower with a ZHR of 100 typically gives a few dozen meteors an hour from a good rural site, and perhaps 10 to 20 from a suburban backyard.
Where and how to look
- No binoculars or telescope. Meteors appear anywhere and last a second or less. Your eyes, with their huge field of view, are the right instrument.
- Get as dark as you can. Every step darker adds meteors. See dark adaptation and light pollution.
- Lie back. A reclining chair or a mat with a sleeping bag lets you take in a big piece of sky without neck strain.
- Look about halfway up, into the darkest part of the sky. You don’t need to stare at the radiant. Meteors near it have short trails; those 30 to 50 degrees away are often longer and more striking.
- Check that a meteor belongs. Trace its path backward. If it points to the radiant, it’s a shower member; if not, it’s one of the random “sporadic” meteors seen every night.
The major showers
Dates shift by a day or so from year to year; each shower’s page has this year’s peak.
| Shower | Peak | Notes |
|---|---|---|
| Quadrantids | Early January | Strong but very short peak; best from the Northern Hemisphere |
| Lyrids | Late April | Moderate, occasional surprises |
| Eta Aquariids | Early May | Debris of Halley’s Comet; best before dawn from southern latitudes |
| Perseids | Mid-August | Reliable, bright, warm nights in the north |
| Orionids | Late October | Also from Halley’s Comet; fast meteors |
| Leonids | Mid-November | Usually modest; historic storms in some years |
| Geminids | Mid-December | Often the year’s best; good from mid-evening |
Photographing meteors
Put a camera on a tripod, use the widest lens you have at its widest aperture, focus on a bright star, and take continuous exposures of 10 to 30 seconds for as long as the battery lasts. Most frames will be empty; the reward is the one that isn’t. Phones in night mode can catch the brightest meteors too, but keep the screen dim and turned away from your eyes.