Asteroids, Comets, and Meteors: What Makes Each Celestial Object Unique

Asteroids, comets, and meteors are all small solar system objects, but they differ in composition and behaviour.

Highlights

• Asteroids are rocky remnants from the early solar system
• Comets are icy objects with characteristic tails
• Meteors are fragments that burn up in Earth's atmosphere

Planetary scientists from NASA explain that while asteroids, comets, and meteors are all small celestial objects orbiting the Sun, they differ greatly in composition, appearance, and behaviour. These distinctions help scientists understand more about our solar system and the unique roles each type of object plays.

Asteroids: Rocky Remnants of the Early Solar System

Asteroids are small, rocky objects that circle the Sun, explains NASA JPL scientist Ryan Park. Typically appearing as points of light in telescopes, most are concentrated within a region called the asteroid belt, located between Mars and Jupiter. This belt contains a range of asteroid shapes and sizes, from rounded forms to elongated structures, with some even accompanied by small moons.

These ancient rocks are considered to be remnants from the early solar system, carrying clues about the conditions and materials present billions of years ago.

Comets: Icy Bodies with Characteristic Tails

Comets, in contrast to asteroids, contain more ice and dust than rock, giving them a unique composition. When a comet nears the Sun, the heat causes its icy surface to vaporise, resulting in the release of gas and dust. This process produces a tail that stretches behind the comet, which appears hazy when observed through telescopes.

Comets are often distinguished by this tail, which is formed by solar radiation pushing dust and gas away from the comet's core. The tails are a characteristic feature that differentiates them from asteroids and makes them particularly interesting to study.

Meteors and Meteoroids: Pieces of Asteroids and Comets Entering Earth's Atmosphere

When discussing meteors, it's essential to understand the term "meteoroid," which refers to a small fragment of an asteroid or comet, often created from a collision or breakup of these larger bodies. Once a meteoroid approaches Earth and enters its atmosphere, it is then called a meteor.

Travelling at very high speeds, meteors burn up upon entry, creating bright streaks of light in the sky that people often refer to as "shooting stars." If a meteor survives this fiery descent and lands on Earth, it becomes known as a meteorite.

A Comparative Overview

These planetary objects, though similar in their solar orbits, hold unique compositions and behaviours. Asteroids are solid and rocky, comets are icy and produce tails, and meteors are small fragments that create bright streaks in Earth's sky.