Asteroids and Meteoroids
Our solar system is filled with billions of smaller, fascinating objects—the cosmic debris left over from the formation of the Sun and planets 4.6 billion years ago.
While they may seem interchangeable, astronomers have specific names for these rocky, icy, and dusty wanderers, often based entirely on where they are and what state they are in as they travel through space and interact with Earth.
Six Names for Cosmic Debris
Meteoroid
The TravelerA small, natural, solid object traveling through space, generally ranging in size from a grain of dust up to about a meter in diameter. They are essentially fragments of larger celestial bodies, such as pieces chipped off of asteroids or the icy remnants of comets. The vast majority travel aimlessly throughout the inner solar system, representing the most common form of cosmic debris encountered by Earth.
Meteor
The ShowThe visual phenomenon—the streak of light—that occurs when a meteoroid enters a planet’s atmosphere at high speed and burns up due to intense friction with the air molecules. Commonly called a “shooting star,” this flash is not the rock itself glowing, but the superheated gas surrounding the vaporizing particle. Most meteors disintegrate completely in the mesosphere.
Meteorite
The SurvivorThe solid remnant of a meteoroid that successfully survives its fiery passage through the atmosphere and lands on the Earth’s surface. These cosmic survivors are valuable to scientists because they are pristine samples of material from the early solar system, offering direct clues about the composition of other celestial bodies.
Meteoroid Shower
The Annual DisplayA celestial event that occurs when the Earth, in its orbit, passes through a concentrated stream of dust and debris left behind by a specific comet. As Earth ploughs through this trail, the particles strike the atmosphere, producing dozens or even hundreds of meteors per hour, all appearing to originate from the same radiant point in the sky.
Asteroid
The Bigger RockA large, rocky, or metallic body that orbits the Sun, significantly bigger than a meteoroid. These bodies are considered minor planets or planetoids and can range in size from one meter to hundreds of kilometers. Most are clustered in the Asteroid Belt, between the orbits of Mars and Jupiter—the failed building blocks of a planet that never coalesced.
Comet
The Dirty SnowballA small, icy body in the outer solar system, composed primarily of frozen gases, water ice, dust, and rock. When a comet’s highly elliptical orbit brings it close to the Sun, the ice sublimates, creating a hazy atmosphere called a coma and often a brilliant, long tail, always pushed away from the Sun by the solar wind and radiation pressure.
