A shooting star is not a star. It is a speck of dust or rock from space hitting Earth's atmosphere so fast that it burns up in a streak of light. People in dozens of cultures have read meaning into them — a wish granted, a soul passing — and they are easy to see if you know when to look.
Four words for space rock
NPS
| Word | What it is |
|---|---|
| Meteoroid | a chunk of ice or rock in space, from a grain of sand to a boulder |
| Asteroid | much bigger — from the size of a small house to miles across |
| Meteor | a meteoroid burning up in Earth's atmosphere: the "shooting star" |
| Meteorite | the part of a meteor that survives the trip down and hits the ground |
Space debris arrives constantly. NASA scientists estimate that about 48 tons of meteoritic material falls on Earth every day, nearly all of it burning up on the way down. So you can see a meteor on any clear night, with luck.
The night sky and a shooting star at Isle Royale National Park. NPS / Jacob W. Frank
Meteor showers
The best odds are during a meteor shower, when many meteors hit the atmosphere in a short time. Showers come around on the same dates every year, because Earth's orbit carries it through the same trails of debris shed by comets. The meteors in a shower seem to fly out from one point in the sky, and each shower is named for the star or constellation nearest that point.
The colour of a meteor tells you what it's made of:
| Colour | Element |
|---|---|
| orange-yellow | sodium |
| yellow | iron |
| blue-green | magnesium |
| violet | calcium |
| red | nitrogen and oxygen in the air itself |
The year's big showers
| Shower | Usual peak | Meteors per hour at best |
|---|---|---|
| Quadrantids | early January | 120 |
| Lyrids | late April | 18 |
| Eta Aquariids | early May | 60 |
| Southern Delta Aquariids | late July | 20 |
| Perseids | mid-August | 100 |
| Orionids | late October | 22 |
| Leonids | mid-November | 15 |
| Geminids | mid-December | 120 |
| Ursids | late December | 10 |
How many you actually see depends on the moon and the weather, so a shower can be spectacular one year and faint the next. NASA publishes details of each shower.
The Park Service's card: shooting stars are not stars; about 48 tons of space debris falls on Earth every day, mostly burning up; the best time to see them is a meteor shower; and five to mark on the calendar — the Quadrantids, Eta Aquariids, Perseids, Leonids and Geminids.
Going out to look
- Pick a shower from the table and put it in your calendar.
- Find a dark place — the Park Service has a guide to where to stargaze, near home or in a park, and a primer, Stargazing 101.
- Children can become Junior Ranger Night Explorers.
- Keep your own sky dark: protecting night skies at home.
Sources
Written from "I Didn't Know That!: Shooting Stars", National Park Service, part of its I Didn't Know That! series; a work of the United States government in the public domain. The 48-ton figure is NASA's estimate, as cited there.
Licence: CC0 1.0 (public domain) · Adapted from www.nps.gov
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