Difference between asteroids, meteors, and comets

Difference between asteroids, meteors, and comets

Think of an asteroid as a big rocky object — but smaller than a planet — orbiting the sun. Most are found in the asteroid belt, a ring of debris between the orbits of Mars and Jupiter. This rocky rubble is left over from the making of the solar system about 4.6 billion years ago. They come in different shapes, and some even travel with their own circling moonlets.

Like an asteroid, a comet also orbits the sun, but it's a bright ball of ice, dust, and rock that formed in the outer solar system. When the ancient dirty snowball approaches the sun, its ice starts to disintegrate. Sometimes shooting stars are confused for comets because they create a glowing streak, but the millions-of-miles-long tail of a comet is its ice and dust vaporizing in space.

Meteors, on the other hand, (or "meteoroids" as astronomers sometimes call them while the rocks are in space), are small chunks of asteroids, comets, or planets that usually broke off during some sort of astronomical collision. Scientists estimate about 48.5 tons of billions-of-years-old meteor material rain down on Earth daily. Most of those space rocks evaporate in the atmosphere or fall into the ocean, which covers over 70 percent of the planet.

Those that survive the brutal inferno of falling through the atmosphere — reaching around 3,000 degrees Fahrenheit(opens in a new tab) due to air friction, according to the American Museum of Natural History — are referred to as meteorites.

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 "Asteroids are rocky, comets are icy, and meteors are much smaller and are the shooting stars that you see up in the sky."

More than 60,000 meteorites have been discovered on Earth. The vast majority come from asteroids, but a small sliver, about 0.2 percent(opens in a new tab), come from Mars or the moon, according to NASA. At least 175 have been identified as originating from the Red Planet. (And, in case you were wondering, Mars gets its fair share of meteorites, too.)

Many space rocks that made the full journey to the Earth's surface are found in Antarctica because they're relatively easier to spot on the vast frozen plains. The dark lumps stand out against the snowy-white landscape, and even when meteorites sink into the ice, the glaciers churning beneath help to resurface the rocks on blue ice fields.

Despite the quantity of meteors pummeling the planet daily, these extraterrestrial sightings are rare(opens in a new tab), said Don Yeomans, a former planetary scientist at NASA's Jet Propulsion Laboratory, before retiring. Only half of the world is in darkness at any given time, and two-thirds of that is over water where hardly anyone lives. Eliminate the areas experiencing bad weather conditions or urban light pollution, too.

"Few people are even looking up at the appropriate moment," he said in a 2010 NASA feature. "When you put it all together, it's almost notable that anybody notices these meteors at all."