A meteoroid is a small rocky or metallic object orbiting the Sun. They are smaller than asteroids, ranging from small rocks to boulders. When a meteoroid enters Earth's atmosphere, it becomes a meteor , producing a bright streak of light. Most meteoroids completely burn up in the atmosphere. If any part of the meteoroid survives the fiery passage and reaches the ground, it is then called a meteorite .

What happens when a meteoroid enters the Earth's atmosphere?

When a meteoroid enters Earth's atmosphere, it is traveling at a very high velocity. The minimum velocity is 11 km per second (25,000 miles per hour), which is many times faster than a bullet. Due to the energetic collision with atmospheric atoms and molecules, frictional heating causes the meteoroid's surface to melt and vaporize, also heating the surrounding air. This produces a luminous phenomenon called a meteor , also known as shooting stars or falling stars. Most meteoroids burn up completely in the upper atmosphere. If a meteoroid survives the plunge and lands on Earth's surface, it is called a meteorite .

What is the difference between a meteor and a meteoroid?

A meteoroid is a small rock or metal object floating in space. When it enters Earth's atmosphere, it becomes a meteor , which is the streak of light seen as the object burns up due to friction. Most meteoroids completely burn up in the atmosphere. If any part of the meteoroid survives the fiery journey and lands on Earth, it is then called a meteorite .

Why do meteors sometimes create bright streaks in the sky?

When a meteoroid enters Earth's atmosphere, it collides with atmospheric atoms and molecules at high speeds, typically over 11 kilometers per second. This generates frictional heating , causing the meteoroid's surface to vaporize and ionize, also ionizing the surrounding air. The excitation of these atoms produces a luminous region , resulting in the glowing streak we call a meteor , or shooting star.

What is a meteor shower and how does it occur?

A meteor shower is a rise in the number of meteors observed in the sky over a short period. These meteoroids enter Earth’s atmosphere at the same time of year and from the same direction, traveling in parallel paths. Most meteor showers are associated with active or defunct comets . As Earth passes through the orbit of a comet, it collides with streams of debris, which produces a meteor shower. Showers are named for the constellation where the meteors seem to originate.

What happens if a meteor survives the atmosphere and lands on Earth?

When a meteoroid survives its journey through the Earth's atmosphere and lands on the surface, it is then called a meteorite . The effect of the impact depends largely on the size of the meteorite. Small meteorites For meteoroids that are about a kilogram or less, the impact is usually minor, and may go unnoticed. Many are only recovered because they strike an object, like a house or car, that draws attention to the event. Large meteorites Very large meteoroids (100 meters to several kilometers in diameter) pass through the atmosphere without slowing and strike the surface at tremendous speeds, releasing huge amounts of kinetic energy and creating impact craters . The geologic record shows that Earth has been struck by very massive meteoroids. Some scientists believe that these impacts may have played a major role in the origin of life on Earth and the course of biological evolution.

Meteor and meteoroid

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The Difference Between Meteors, Meteorites, and Meteoroids

Illustration of the 1870 Leonid meteor shower with bright meteor trails in a starry night sky above clouds, and a hot air balloon floating at right.

dust particles from Comet Wild 2 and interplanetary space

At a Glance

meteor summary

Meteor and meteoroid

atmospheric phenomenon

Also known as: falling star, shooting star

Written by

Conel M.O'D. AlexanderAll

Fact-checked by

Britannica Editors

Last updated

Nov. 11, 2026 •History

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Don't miss: Meteor showers, fireballs, and a supermoon light up November's night sky • Nov. 6, 2026, 3:21 AM ET (Science Daily)

Meteor and meteoroid, respectively, a glowing streak in the sky (meteor) and its cause, which is a relatively small stony or metallic natural object from space (meteoroid) that enters Earth’s atmosphere and heats to incandescence. In modern usage the term meteoroid, rather than being restricted to objects entering Earth’s atmosphere, is applied to any small object in orbit around the Sun having the same nature as those that result in meteors.

When a meteoroid enters Earth’s atmosphere, it is traveling at very high velocity—more than 11 km per second (25,000 miles per hour) at minimum, which is many times faster than a bullet leaving a gun barrel. Frictional heating, produced by the meteoroid’s energetic collision with atmospheric atoms and molecules, causes its surface to melt and vaporize and also heats the air around it. The result is the luminous phenomenon recognized as a meteor. Popular synonyms for meteors include shooting stars and falling stars. The vast majority of meteoroids that collide with Earth burn up in the upper atmosphere. If a meteoroid survives its fiery plunge through the atmosphere and lands on Earth’s surface, the object is known as a meteorite.

The term meteoroid is usually reserved for chunks of matter that are approximately house-sized—i.e., some tens of metres across—and smaller. Meteoroids are believed to be mostly fragments of asteroids and comets and are placed, with them, in the category of solar system objects known as small bodies. A few meteoroids also have come from the Moon, Mars, Vesta, and possibly Mercury. The smallest meteoroids, those less than a few hundred micrometres across (about the size of a period on a printed page), are called interplanetary dust particles or micrometeoroids.

The terms meteoroid and meteor (and meteorite as well) are sometimes confusingly interchanged in common usage. Meteor in particular is often applied to a meteoroid hurtling through space, to an incandescent meteoroid (rather than just its luminous streak) in the atmosphere, or to an object that has hit the ground or a human-made object. An example of the last case is found in the name Meteor Crater, a well-known impact structure in Arizona, U.S.

Meteor and meteoroid

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