Asteroid vs Comet vs Meteor
Discover the key differences between these space objects, from their composition and origins to their spectacular appearances in our night sky.
Quick Answer
Asteroids are rocky objects, comets are icy bodies that develop tails near the Sun, and meteors are the bright streaks we see when small particles burn up in Earth's atmosphere. The main difference is composition: asteroids are rock and metal, comets are ice and dust.
- Made of rock and metal
- Mainly in the asteroid belt
- Circular orbits, inner solar system
- Ice, dust, and frozen gases
- Kuiper Belt & Oort Cloud
- Develops tails when near the Sun
- Small rock or metal fragments
- Burns up in Earth's atmosphere
- Bright streak of light
Detailed Comparison
| Property | Asteroid | Comet | Meteor |
|---|---|---|---|
| Composition | Rock and metal (silicates, iron, nickel) | Ice, dust, rock, and frozen gases (water, CO2, methane) | Small rock or metal fragments |
| Size | 1 meter to 1,000 km (Ceres is largest) | 1-50 km nucleus (tail can extend millions of km) | Dust grain to 1 meter |
| Location | Mainly asteroid belt (between Mars & Jupiter) | Kuiper Belt & Oort Cloud (outer solar system) | Earth's atmosphere (when burning up) |
| Orbit | Mostly circular, same plane as planets | Highly elliptical, can be inclined | N/A (becomes meteor when entering atmosphere) |
| Tail | No tail | Develops tail when near Sun (gas and dust) | Bright streak (burning trail) |
| Nickname | "Minor planets" or "planetoids" | "Dirty snowballs" or "icy dirt balls" | "Shooting stars" |
What is a Comet?
- Nucleus
The solid core (1-50 km), made of ice, dust, and rock - often called a 'dirty snowball'
- Coma
A fuzzy atmosphere of gas and dust surrounding the nucleus when near the Sun
- Tail(s)
Two types: blue ion tail (gas) points directly away from Sun, white/yellow dust tail curves along orbit
- • Comets are often called 'dirty snowballs' or 'icy dirt balls'
- • A comet's tail always points away from the Sun due to solar wind
- • Short-period comets come from the Kuiper Belt, long-period from the Oort Cloud
- • Halley's Comet returns every 75-76 years (next: 2061)
- • Comets may have delivered water and organic molecules to early Earth
What is an Asteroid?
- C-type (Carbonaceous)
Most common (~75%), dark, carbon-rich, found in outer asteroid belt
- S-type (Silicaceous)
Second most common (~17%), stony, silicate minerals, inner asteroid belt
- M-type (Metallic)
Rare but valuable, iron-nickel composition, may be cores of destroyed planetesimals
- • Over 1.3 million asteroids have been catalogued in our solar system
- • Ceres is the largest asteroid (940 km) and is also classified as a dwarf planet
- • The total mass of all asteroids is less than Earth's Moon
- • Some asteroids have their own moons (like Ida and its moon Dactyl)
- • Near-Earth asteroids are monitored for potential impact risks
Meteor vs Meteorite vs Meteoroid
Meteoroid
A small rock or particle traveling through space, ranging from dust grains to 1 meter in size
Meteor
The bright streak of light when a meteoroid burns up in Earth's atmosphere - also called a 'shooting star'
Meteorite
A meteoroid that survives passage through the atmosphere and lands on Earth's surface
While most comets originate within our solar system (Kuiper Belt or Oort Cloud), a few rare objects come from other star systems entirely. These interstellar objects travel on hyperbolic orbits - they pass through once and never return.
1I/'Oumuamua
Discovered 2017, first confirmed interstellar object, unusual elongated shape, no visible coma
2I/Borisov
Discovered 2019, first confirmed interstellar comet, showed typical comet activity with coma and tail
3I/ATLAS
Discovered July 2025, third interstellar object, currently being tracked as it passes through our solar system
Frequently Asked Questions
The main difference is composition: asteroids are made of rock and metal, while comets are made of ice, dust, and frozen gases. Asteroids orbit in the inner solar system (mainly the asteroid belt), while comets come from the outer solar system (Kuiper Belt and Oort Cloud). Comets develop tails when near the Sun; asteroids do not.
A meteoroid is a small rock or particle in space. When a meteoroid enters Earth's atmosphere and burns up, creating a streak of light, it's called a meteor (or 'shooting star'). If any part survives and lands on Earth, it becomes a meteorite.
Some objects blur the line between asteroids and comets. 'Active asteroids' or 'main-belt comets' are objects in the asteroid belt that occasionally show comet-like activity. Scientists now recognize that the distinction isn't always clear-cut.
Comets are made of ice (water, carbon dioxide, methane, ammonia), dust, and rocky material. They're often called 'dirty snowballs' because they're primarily ice mixed with dark organic material. When heated by the Sun, the ice sublimates (turns to gas), creating the characteristic coma and tail.
Most comets come from two regions: the Kuiper Belt (30-50 AU from the Sun, source of short-period comets) and the Oort Cloud (2,000-100,000 AU away, source of long-period comets). Some rare comets, like 3I/ATLAS, come from outside our solar system entirely - these are called interstellar comets.
An interstellar comet is a comet that originated from another star system and is passing through our solar system. Only three have been confirmed: 1I/'Oumuamua (2017), 2I/Borisov (2019), and 3I/ATLAS (2025). They travel on hyperbolic orbits and will never return to our solar system.