Meteorite

A meteorite is a rock that comes from outer space and lands on the surface of a planet or moon. When a space rock enters Earth's atmosphere, it heats up because of friction and air pressure. This makes it glow brightly, creating what we call a meteor or a shooting star. If it is very bright, it is called a "bolide". When this space rock finally reaches the ground, it is called a meteorite.

Meteorites can be very different in size and type. Some are made mostly of rocky material, called stony meteorites. Others are made of metal, called iron meteorites, and some have both rock and metal, called stony-iron meteorites. Scientists study these rocks to learn about space and how our solar system formed.

Most meteorites that fall to Earth come from broken pieces of asteroids. These space rocks have broken apart and their pieces continue to travel through space, sometimes ending up on Earth. Studying meteorites helps us understand more about the materials and history of our solar system.

Fall phenomena

When small space rocks, called meteoroids, enter Earth's atmosphere, most of them break apart. About five to ten times each year, pieces make it to the ground where scientists can study them. Only a few meteorites are big enough to make large craters. Instead, they usually land at their slowest speed and might make only a small pit.

Big meteoroids can hit Earth very hard, creating big craters. These crashes can be very powerful. Iron meteoroids often make these craters because they can pass through the atmosphere without breaking apart. Examples include Barringer Meteor Crater, Odessa Meteor Crater, Wabar craters, and Wolfe Creek crater. Smaller rocky or icy objects, like some comets or asteroids, usually break apart in the atmosphere and do not make craters. Very large rocky objects are rare but can make big craters, though they often destroy completely with no pieces left behind.

When meteoroids enter the atmosphere, they can create bright lights, sometimes as bright as the sun. These lights can be many colors, such as yellow, green, or red. Sometimes, loud sounds like booms or explosions can be heard after the light passes. After the light is gone, a dust trail might stay in the sky for a few minutes.

As meteoroids heat up in the atmosphere, their surfaces melt and change shape. Some develop special patterns called regmaglypts. When they slow down, a thin, dark layer forms on their surface. Depending on the type of meteorite, this layer can be very thin or affect a bit deeper into the rock. Some meteorites land very hot, while others can be cold enough for water to form on them.

When meteoroids break apart in the sky, they can create showers of meteorites. These showers can have just a few pieces or thousands, and they usually fall over a long, stretched-out area called a strewn field. The biggest pieces are often found at the far end of this area.

Classification

Meteorites are rocks from space that fall to Earth. Most are stony meteorites, which come in two types: chondrites and achondrites. Chondrites contain small, round particles called chondrules and make up about 86% of meteorites. They are very old and might be pieces from the asteroid belt.

Achondrites, which make up about 8% of meteorites, do not have chondrules and are similar to rocks from Earth. Some might come from the Moon or Mars. Iron meteorites, made of iron and nickel, are about 5% of those that fall. They may come from the cores of small planets that broke apart. Stony-iron meteorites are a mix of rock and metal and make up the remaining 1%.

Frequency

Meteorites falling to Earth is actually quite common. Each year, there are about 8-9 meteorite landings for every 1,000,000 square kilometers, leaving behind more than 1 kilogram of material. Many of these meteorites are small, but some are much larger.

Scientists have found that most meteorites on Earth come from the break-up of just three asteroids in space. Only a small part of meteorites can be traced back to places like the Moon, Mars, or a special asteroid named Vesta.

Weathering

See also: Meteorite weathering

Many meteorites come from the very beginning of our Solar System and are the oldest materials we have on Earth. Scientists study how water, salt, and oxygen change meteorites over time to learn how much they have been altered. They use special scales to measure this change, especially for common meteorites called ordinary chondrites.

Sometimes, scientists find very old meteorites that have been changed so much by Earth's weather that they look like rocks from long ago. In places like Sweden, many of these old meteorites have been found in stone layers. Even though they look different now, scientists can still tell they came from space by studying tiny pieces inside them. These meteorites likely all came from the same place in space, far from Earth, and may be from a type we no longer see falling to our planet.

Collection

See also: Impact event

A "meteorite fall" is when a meteorite is collected after people or machines see it arrive on Earth. Other meteorites are called "meteorite finds." There are over 1,100 documented falls listed in databases, most of which are kept in modern collections. As of January 2019, the Meteoritical Bulletin Database had 1,180 confirmed falls.

Most meteorite falls are collected based on stories from people who saw a bright light in the sky or heard something hit the ground. Even though meteorites fall everywhere on Earth, verified falls are usually found in places with lots of people, like Europe, Japan, and northern India.

A few meteorite falls have been caught by cameras and found after scientists calculated where they landed. The first of these was the Příbram meteorite, which fell in Czechoslovakia (now the Czech Republic) in 1959. Two cameras took pictures of the bright light, helping scientists find the meteorite pieces and learn its path through space.

After Příbram, other countries started programs to study falling meteorites. The Prairie Network, run by the Smithsonian Astrophysical Observatory from 1963 to 1975 in the midwestern US, found the Lost City meteorite. Canada’s Meteorite Observation and Recovery Project, from 1971 to 1985, found the Innisfree meteorite in 1977. The European Fireball Network discovered the Neuschwanstein meteorite in 2002. NASA also has a system that detects meteors and calculates their paths over the southeast USA.

Until the twentieth century, only a few hundred meteorite finds had been discovered. Over 80% of these were easy to tell apart from ordinary rocks because they were made of iron or stony-iron. Today, there are more than 30,000 meteorite finds in the world’s collections, thanks to discoveries by Harvey H. Nininger.

Meteorites that land in Canada are protected under the Cultural Property Export and Import Act. In July 2024, security footage recorded a meteorite crashing into a house in Marshfield, Prince Edward Island. This is believed to be the first time such an event has been caught on camera. It was named the Charlottetown meteorite after the nearby city.

Nininger searched for meteorites in the Great Plains of the United States, where the land had few rocks. Between the late 1920s and the 1950s, he found over 200 new meteorites, mostly stony types.

In the late 1960s, Roosevelt County, New Mexico became a great place to find meteorites. After a few were found in 1967, a campaign to tell people about meteorites led to nearly 100 new ones being found in the next few years, many by a single person, Ivan Wilson. In total, nearly 140 meteorites have been found there since 1967.

Since the mid-1960s, meteorite hunters have searched the dry areas of the southwestern United States. Thousands of meteorites have been found in the Mojave, Sonoran, Great Basin, and Chihuahuan Deserts, often on dry lake beds. Major finds include the three-tonne Old Woman meteorite, displayed at the Desert Discovery Center in Barstow, California, and the Franconia and Gold Basin meteorite areas, where hundreds of kilograms have been found.

A few meteorites were found in Antarctica between 1912 and 1964. In 1969, a Japanese expedition found nine meteorites on a blue ice field near the Yamato Mountains. This showed that moving ice sheets can gather meteorites in certain spots. More searches followed, and nearly 700 meteorites were found.

The United States started its own search in Antarctica along the Transantarctic Mountains, called the Antarctic Search for Meteorites (ANSMET) program. European teams and others also searched for Antarctic meteorites.

In the same time period, meteorite hunters found many in the hot deserts of Australia, especially on the Nullarbor Plain in Western Australia and South Australia. The flat, dry land allowed meteorites to stay on the surface for thousands of years.

In the Sahara Desert, meteorites were found in large numbers starting in the late 1980s. Favorable conditions made them easy to spot. By the late 1990s, many private collectors were searching for meteorites there.

Meteorite markets grew in the late 1990s, especially in Morocco. Many meteorites, known as “Northwest Africa” meteorites, were sold without details about where they were found. Some important meteorites, like Tissint and NWA 7034, were found this way.

In 1999, meteorite hunters found many in the deserts of southern and central Oman, especially in the Dhofar and Al Wusta regions. These areas have produced thousands of meteorites, including some from the Moon and Mars.

In human affairs

Meteorites have been important to people for a very long time. They have been used in special ceremonies and religious practices, and people have written about them when they fall from the sky.

Some ancient cultures thought meteorites came from the gods. For example, a temple in Ephesus may have started because people found a meteorite they believed fell from Jupiter. Native American cultures also used meteorites in ceremonies. In 1915, a large meteorite was found in an old burial site in Arizona, wrapped in feathers.

People have written about meteorites falling for many years. In 1064, a Chinese writer described seeing a bright object in the sky and later finding a hot meteorite. In 1492, a meteorite fell in Ensisheim, and scientists later proved these rocks come from space.

Sometimes meteorites hit people or buildings. In 1954, a meteorite crashed through a roof in Alabama and hurt someone below. In 2021, another meteorite went through a roof in Canada and landed on a bed, but no one was hurt.

Notable examples

See also: List of largest meteorites on Earth

Meteorites are named after the places where they were found, often a nearby town or special feature. If many meteorites are found in one spot, they may have a number or letter added to the name. Scientists and collectors use the name chosen by the Meteoritical Society.

Terrestrial

• Allende – The largest known type of meteorite called a carbonaceous chondrite, found in Chihuahua, Mexico, in 1969.
• Allan Hills A81005 – The first meteorite known to come from the Moon.
• Allan Hills 84001 – A meteorite from Mars that some thought might show signs of life.
• The Bacubirito Meteorite – A very heavy meteorite estimated to weigh between 20 and 30 short tons.
• Campo del Cielo – A group of iron meteorites linked to a field of at least 26 craters in West Chaco Province, Argentina. Together, they weigh over 100 tonnes.
• Canyon Diablo – Linked to Meteor Crater in Arizona.
• Cape York – One of the largest meteorites ever found. A huge piece called "Ahnighito" is displayed at the American Museum of Natural History; it is the largest meteorite on show in any museum.
• Gibeon – A large iron meteorite found in Namibia, creating the biggest known area where meteorites spread out.
• Hoba – The largest intact meteorite known.
• Kaidun – An unusual type of meteorite called a carbonaceous chondrite.
• Mbosi meteorite – A big, unusual iron meteorite found in Tanzania, weighing 16 metric tons.
• Murchison – A meteorite found to contain important building blocks for life.
• Nōgata – The oldest meteorite whose falling date is known exactly: May 19, 861, in Nōgata.
• Orgueil – A famous meteorite because it is very ancient and contains special grains from before the solar system formed.
• Sikhote-Alin – A big iron meteorite that fell to Earth on February 12, 1947.
• Tucson Ring – A meteorite shaped like a ring, once used by a blacksmith, now at the Smithsonian.
• Willamette – The largest meteorite ever found in the United States.
• 2007 Carancas impact event – In September 2007, a stony meteorite possibly weighing up to 4000 kilograms made a 13-meter wide crater near Carancas, Peru.
• 2013 Russian meteor event – In February 2013, a very large asteroid entered the atmosphere above Chelyabinsk, Russia, creating a bright fireball in the sky. Small pieces of this meteorite have been found nearby.

Extraterrestrial

• Bench Crater meteorite (Apollo 12, 1969) and the Hadley Rille meteorite (Apollo 15, 1971) – Pieces of asteroids found among samples collected on the Moon.
• Block Island meteorite and Heat Shield Rock – Iron meteorites found on Mars by the Opportunity rover, along with four others. The Spirit rover also found two nickel-iron meteorites. (See also: List of rocks on Mars)

Large impact craters

See also: List of impact craters on Earth

• Acraman crater in South Australia (90 kilometres or 56 miles wide)
• Ames crater in Major County, Oklahoma (16 kilometres or 9.9 miles wide)
• Brent crater in northern Ontario (3.8 kilometres or 2.4 miles wide)
• Chesapeake Bay impact crater (90 kilometres or 56 miles wide)
• Chicxulub crater off the coast of the Yucatán Peninsula (170 kilometres or 110 miles wide)
• Clearwater Lakes a double crater impact in Québec, Canada (26 and 36 kilometres or 16 and 22 miles wide)
• Lonar crater in India (1.83 kilometres or 1.14 miles wide)
• Lumparn in Åland, in the Baltic Sea (9 kilometres or 5.6 miles wide)
• Manicouagan Reservoir in Québec, Canada (100 kilometres or 62 miles wide)
• Manson crater in Iowa (38 kilometres or 24 miles wide, buried)
• Meteor Crater in Arizona, also called "Barringer Crater", the first confirmed impact crater on Earth. (1.2 kilometres or 0.75 miles wide)
• Mjølnir impact crater in the Barents Sea (40 kilometres or 25 miles wide)
• Nördlinger Ries crater in Bavaria, Germany (25 kilometres or 16 miles wide)
• Popigai impact structure in Russia (100 kilometres or 62 miles wide)
• Siljan Ring in Sweden, the largest crater in Europe (52 kilometres or 32 miles wide)
• Sudbury Basin in Ontario, Canada (250 kilometres or 160 miles wide)
• Ungava Bay in Québec, Canada (260 by 320 kilometres or 160 by 200 miles)
• Vredefort impact structure in South Africa, the largest known impact structure on Earth (300 kilometres or 190 miles wide from a meteorite about 10 kilometres or 6.2 miles wide).

Disintegrating meteoroids

• Tunguska event in Siberia in 1908 (no crater formed)
• Chelyabinsk event in Russia in 2013 (no known crater)