
We're all fascinated by meteorites, ancient stony visitors from outer space. But what exactly are they, how do they get here and how can you tell if you've found one?
Most meteorites are fragments of material left over from the time when the Solar System was forming. Some never got scooped up by the gravity of a newly created planet, so they're orbiting the Sun alone. Others ended up as part of an asteroid or in the nucleus of a comet. Some meteorites come from other planets, dwarf planets or moons, including lunar and Martian fragments that were ejected into space following an impact.
So you can see why these objects capture our imaginations. They offer us a chance to study the conditions of the early Solar System or the surface of another planet without having to go there. Indeed, meteorites are still the only samples we have from Mars or some of the dwarf planets like Ceres, so they are an invaluable source of information.
How do these fragments end up on Earth? Over millions of years, the gravity of the planets, especially Jupiter, has pushed asteroids into particular orbits, such as the asteroid belt between Mars and Jupiter. Collisions between asteroids create large fragments, small particles and dust, some of which get nudged into new orbits that take them towards Earth, where they burn up in our atmosphere to form a meteor.
Comets that formed far beyond the orbit of Neptune can also be nudged into new orbits that bring them to the inner Solar System. As a comet nears the Sun, its icy nucleus starts to sublimate, releasing a trail of trapped dust. When Earth passes through this dust, these particles will also burn up in our atmosphere as meteors. Cometary debris is responsible for most of our meteor showers.
What are the chances?
この記事は BBC Sky at Night Magazine の February 2025 版に掲載されています。
7 日間の Magzter GOLD 無料トライアルを開始して、何千もの厳選されたプレミアム ストーリー、9,000 以上の雑誌や新聞にアクセスしてください。
すでに購読者です ? サインイン
この記事は BBC Sky at Night Magazine の February 2025 版に掲載されています。
7 日間の Magzter GOLD 無料トライアルを開始して、何千もの厳選されたプレミアム ストーリー、9,000 以上の雑誌や新聞にアクセスしてください。
すでに購読者です? サインイン

Putting cosmic rays to work
These penetrating interstellar particles have applications from astronomy to archaeology

Set up your first imaging sequence
How to automate and coordinate your gear over multiple nights of imaging

The Universe without gravity
Life with no gravity might sound a fun idea, but as Govert Schilling explains, shutting off this pivotalforce would spell disaster for Earth and beyond

How to blend images taken with different camera setups
Combine data captured at varied focal lengths to create rich, deep images

INSIDE THE SKY AT NIGHT
Back in September 2021, The Sky at Night show spoke to Carly Howett about NASA's then upcoming Lucy mission. As the spacecraft now approaches its main targets - the Trojan asteroids - we check in with her to see how the mission is going

The science of SCI-FI
We love a good sci-fi film, but do they get the science right? Amy Arthur picks six of the big mistakes made in space films

Seeing in a new light
It's National Astronomy Week this month, so take a tip from Mark Westmoquette and let mindful stargazing change your perspective on your life and problems

GEAR
Charlotte Daniels rounds up the latest astronomical accessories

Q&A WITH A STELLAR ECLIPSE SPECIALIST
Many stars are gravitationally locked inside multi-star systems, but a rare new triple-star system has set a new record for how cosy these clusters can get