Environment & Science

The science of fireballs and shooting stars

A "fireball" streaking across the sky is a Taurid meteor, according to the photographer.
Mike Lewinski/Flickr Creative Commons License

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Mother Nature put on an impressive light show last night.

Around 8 p.m., a fireball flew through the skies of  Southern California. It wowed folks from Santa Barbara to San Diego. There were even sightings as far east as Utah, Nevada and Arizona.

RELATED: See video of the streaking fireball here

Scientists believe the object was part of the yearly Taurids meteor shower, a celestial event caused when our planet's orbit crosses paths with debris left behind by a comet named Encke.

That debris enters the Earth's atmosphere at high speeds, burning up and creating spectacular trails of light.

But unlike most shooting stars, last night's fireball was a meteor of a different magnitude.

Beach-ball sized stone

Shooting stars may loom large in the sky, but NASA's meteor expert Don Yeomans says the fragments that create them are usually just the size of a grain of sand.

Fireballs stem from much larger chunks of space rock.

"The one that was seen last night... was probably a baseball or beach-ball sized stone," Yeomans said.

Fireballs are not uncommon, and the Taurids shower could produce more over the next week.

Shedding cosmic dandruff

Yeomans says when a comet like Encke orbits near the sun, the heat melts the ice within that comet causing it to disintegrate slightly and shed particles.

That cosmic dandruff hangs in the comet's wake. When Earth's orbit crosses that wake, those dust particles hit our atmosphere and create shooting stars.

Of all the yearly meteor showers, the Perseids, the Leonids and the Gemenids are perhaps the best known. But NASA's Don Yeomans says there are dozens of lesser known showers that happen throughout the year.

A streak of color

Fireballs and shooting stars are so bright because as they collide with Earth's atmosphere, friction heats up the meteor and the air around it.

That heat burns up both the rock and the air molecules around it creating those eye-catching streaks of light.

Don Yeomans with NASA's Jet Propulsion Laboratory says the color of that light tells scientists a lot about what the meteor might be made of.

Yellow for instance tends to indicate the presence of iron. A blue-green streak means magnesium might be there. Green is associated with nickel, and a red streak probably means the meteor contained silicates. 

The Taurids meteor shower is expected to peak sometime around November 12th.