What Is The Difference Between Asteroids, Meteors, Meteoroids, And Meteorites?

While we are fascinated (sometimes alarmed) by space rocks hurtling towards Earth, we often fail to distinguish between asteroids, meteoroids, and meteors. Here's a rundown of their differences.

In the vast expanse of space, various celestial objects orbit the Sun, each with distinct characteristics and classifications. Among these are asteroids, meteors, meteorites, and meteoroids. While they may seem similar at first glance, each term describes a different stage or type of 'space rock'.

What Are Asteroids?

Asteroids are relatively large rocky or metallic bodies that orbit the Sun. They are primarily found in the asteroid belt, which lies between the orbits of Mars and Jupiter. Asteroids can vary significantly in size, ranging from a few meters to hundreds of kilometres in diameter. Asteroids are smaller than planets.

Most asteroids are composed of rock and metal, and some may contain organic compounds and even water and ice.

Key Features Of Asteroids

Size: >1 metre in diameter.

Location: Mostly found in the asteroid belt between the orbits of Mars and Jupiter.

Composition: Primarily made up of rock and metal; some contain ice.

Gravitational influence: Due to their size, they exert a gravitational pull and can even have moons.

What are Meteoroids?

Meteoroids are much smaller than asteroids. They are generally defined as fragments or debris from asteroids or comets. They range in size from tiny grains to objects less than 1 metre across. When these small bodies are floating through space, they are classified as meteoroids.

Features Of Meteoroids

Size: Ranges from millimeters to less than 1 metre.

Origin: Often derived from collisions between asteroids or from comets.

Location: Found throughout space but can enter a planet's atmosphere.

What Is A Meteor?

When a meteoroid enters the Earth's atmosphere at high speed, it experiences intense friction with air molecules, causing it to heat up and glow brightly. This phenomenon is what we observe as a meteor, commonly referred to as a "shooting star". Most meteors burn up completely before reaching the Earth's surface.

Features Of Meteors

Appearance: Creates a bright streak of light in the sky.

Process: Result from meteoroids entering the atmosphere and burning due to friction.

Visibility: Often seen during meteor showers when one or many meteoroids enter the atmosphere simultaneously.

What Is A Meteorite?

If a meteoroid survives its fiery passage through the atmosphere and lands on the Earth's surface, it is called a meteorite. Meteorites can vary in size and composition, providing valuable information about their origins and the origins of the solar system.

Key Characteristics Of Meteorites

Survivability: Must survive atmospheric entry without completely burning up.

Types: Can be composed of rock (stony meteorites), metal (iron meteorites), or a combination of both.

Importance: Meteorites offer insights into planetary formation and the history of our solar system

According to NASA, any space rock less than 25 metres (82 feet) will burn up after entering the Earth's atmosphere due to friction. They are unlikely to have any significant impact. Anything larger than that may have some impact locally. But those asteroids which are bigger than 1 km (3,280 m) in diameter have the potential to cause significant damage with global effects.