are cosmic travelers that survive the fiery journey through Earth's atmosphere. These extraterrestrial rocks come in various types, each telling a unique story about our solar system's history and composition.
Studying meteorites helps scientists unravel the mysteries of our cosmic neighborhood. From dating the solar system to understanding planetary formation, these space rocks provide crucial clues about the universe's past and present.
Meteorites: Origins and Types
Meteors vs meteorites
Meteors streak light in the sky as small particles enter Earth's atmosphere at high speeds (shooting stars)
Most originate from comets or burning up in the atmosphere
occurs as the 's surface melts and vaporizes due to atmospheric friction
Meteorites are solid objects that survive passage through Earth's atmosphere and reach the ground
Originate from asteroids, comets, or planetary bodies
Three main types: stony (chondrites), iron (composed of iron-nickel), and stony-iron meteorites (contain both rock and metal)
Often develop a , a thin melted layer on the surface, during atmospheric entry
Methods of meteorite discovery
Visual observation of sightings and eyewitness reports of falls
Radar detection tracks meteors to determine trajectory and potential landing sites
searches systematically explore areas where meteorites likely fell after a fireball event or radar detection
Antarctic searches easily spot meteorites on the white ice surface
Ice flow concentrates meteorites in specific areas leading to many discoveries ()
Meteorite Composition and Research
Types of stone meteorites
Primitive stone meteorites called chondrites contain chondrules
Chondrules are small spherical inclusions formed from molten droplets in the early solar system
Represent some of the oldest and most unaltered material in the solar system (carbonaceous chondrites)
Achondrites are stony meteorites lacking chondrules
Often originate from differentiated planetary bodies (Mars, Moon, Vesta)
Meteorites in solar system dating
Radiometric dating measures the abundance of radioactive isotopes and their decay products in meteorites
Commonly used isotopes: 235U, 238U, and 87Rb
Provides absolute ages for meteorites and the solar system
Chondrites are among the oldest known meteorites
Some dated to 4.56 billion years old
Represents the minimum age of the solar system
ages help constrain the timeline of solar system formation
Provides insights into early stages of planetary formation and differentiation (core, mantle, crust)
Meteorite Impact Effects
form when large meteorites collide with planetary surfaces
Tektites are natural glass objects formed from terrestrial material melted by meteorite impacts
, including micrometeorites, constantly falls to Earth's surface
Iron meteorites often display a distinctive when cut and etched, revealing their crystalline structure
Key Terms to Review (28)
Ablation: Ablation is the process by which the surface of a material is removed through vaporization, chipping, or other erosive processes. In the context of meteors and meteorites, ablation refers to the removal of material from the surface of a meteoroid or meteor as it passes through the Earth's atmosphere.
Achondrite: Achondrites are a type of meteorite that lack chondrules, the small, round particles found in chondrite meteorites. They are formed from the partial or complete melting and recrystallization of their parent body, resulting in a more uniform, crystalline structure compared to chondrites.
Allan Hills: Allan Hills is a region in Antarctica that is known for its high concentration of meteorites. This remote and icy landscape has become a valuable resource for scientists studying the origins and compositions of extraterrestrial materials that have fallen to Earth.
Asteroids: Asteroids are small, rocky bodies that orbit the Sun, primarily found in the asteroid belt between Mars and Jupiter. They vary in size and shape, with some being large enough to be considered dwarf planets if they were spherical.
Carbonaceous Chondrite: Carbonaceous chondrites are a type of stony meteorite that are composed of fine-grained matrix material, including organic compounds and water-bearing minerals. They are some of the most primitive and unaltered materials in the solar system, providing insights into the early formation and composition of the planets.
Chondrite: Chondrites are the most common type of meteorite, making up approximately 86% of all meteorites that fall to Earth. They are stony meteorites that have not been significantly melted or differentiated, preserving the original components of the early solar system.
Chondrule: Chondrules are small, round to elliptical silicate mineral grains found within chondrite meteorites. These millimeter-sized objects are believed to have formed as molten or partially molten droplets that cooled and solidified in the early solar system, providing insights into the conditions and processes that shaped the formation of our planetary bodies.
Cosmic Dust: Cosmic dust refers to the fine particulate matter found throughout the universe, including within interstellar space and in planetary atmospheres. This microscopic debris originates from various sources, such as the outflows of stars, the destruction of meteoroids, and the remnants of comets, and plays a crucial role in the formation and evolution of celestial bodies and the interstellar medium.
Fireball: A fireball is an exceptionally bright meteor that appears to be larger and brighter than a typical shooting star. It is a very luminous meteor, often with a trail, that can be seen over a wide geographic area as it passes through the Earth's atmosphere.
Fusion Crust: The fusion crust is a thin, glassy layer that forms on the surface of a meteorite as it passes through the Earth's atmosphere at high speeds. This distinctive feature is the result of the intense heat and pressure experienced during the meteorite's entry into the planet's atmosphere.
Impact Crater: An impact crater is a depression or hole in the surface of a planet, moon, or other celestial body, formed by the high-speed impact of a meteoroid, asteroid, comet, or other cosmic projectile. These craters are a common geological feature across the solar system and provide valuable insights into the history and evolution of planetary bodies.
Impact craters: Impact craters are depressions on the surface of planets, moons, or other celestial bodies caused by the collision of a meteoroid, asteroid, or comet. These craters often have distinctive features such as raised rims and central peaks.
Iron Meteorite: An iron meteorite is a type of meteorite that is composed primarily of iron, with smaller amounts of other metals such as nickel. These meteorites are some of the rarest and most valuable types of meteorites, as they provide a glimpse into the composition of the Earth's core and the formation of our solar system.
Irons: Irons are a type of meteorite composed primarily of iron and nickel. They originate from the cores of differentiated parent bodies within the solar system.
Martian meteorites: Martian meteorites are fragments of rock ejected from the surface of Mars that have landed on Earth. They provide valuable insights into the geological history and composition of Mars.
Meteor: A meteor is a space rock or piece of debris that burns up as it passes through Earth's atmosphere, creating a visible streak of light in the night sky. Meteors are closely related to the topics of 14.1 Meteors and 14.2 Meteorites: Stones from Heaven, as they are the precursors to the physical objects that reach the Earth's surface, known as meteorites.
Meteorite: A meteorite is a fragment of rock or metal from space that survives its passage through the Earth's atmosphere and lands on the surface. These celestial objects provide valuable information about the early solar system.
Meteorite: A meteorite is a piece of rock or metal from space that has survived passage through the Earth's atmosphere and landed on the surface of a planet or moon. Meteorites are closely related to the topics of 14.1 Meteors and 14.2 Meteorites: Stones from Heaven, as they are the remnants of objects that have entered the Earth's atmosphere.
Meteorite fall: A meteorite fall is an event where a meteoroid survives its passage through Earth's atmosphere and lands on the surface. It is often accompanied by visible phenomena such as a fireball or explosion.
Meteorites: Meteorites are solid pieces of debris from objects like comets, asteroids, or meteoroids that survive their passage through Earth's atmosphere and land on the surface. They provide valuable information about the early solar system.
Primitive meteorites: Primitive meteorites are stony meteorites that have not undergone significant alteration or differentiation since their formation. They are considered some of the oldest and most primitive materials in the solar system, providing insights into its early history.
Stones: Stones, in the context of meteorites, are solid fragments from outer space that survive their journey through Earth's atmosphere and land on the surface. These extraterrestrial rocks provide valuable insights into the early solar system's formation and composition.
Stony Meteorite: A stony meteorite is a type of meteorite that is primarily composed of silicate minerals, such as olivine and pyroxene. These meteorites are the most common type found on Earth, making up approximately 94% of all meteorites that have been recovered and studied.
Stony meteorites are believed to originate from the rocky, inner regions of the solar system, often from the asteroid belt between the orbits of Mars and Jupiter. They provide valuable insights into the formation and composition of the early solar system, as well as the processes that shaped the planets and other celestial bodies.
Stony-Iron Meteorite: A stony-iron meteorite is a type of meteorite that contains a roughly equal mixture of silicate minerals and metallic iron-nickel alloys. These meteorites are considered to be the rarest class of meteorites, making up only about 2% of all known meteorite falls.
Stony-irons: Stony-irons are a type of meteorite that contains nearly equal amounts of silicate minerals and nickel-iron metal. They are among the rarest meteorites, providing valuable insights into the early solar system.
Strewn Field: A strewn field refers to the scattered distribution pattern of meteorite fragments over a large area of the Earth's surface. These fragments are the result of a single meteoroid breaking apart as it passes through the atmosphere, creating a debris field on the ground.
Tektite: Tektites are natural glass objects formed by the impact of meteorites on the Earth's surface. They are typically small, rounded, and have a distinctive glassy appearance, often with a smooth, shiny surface.
Tektites are closely related to the study of meteorites, as they are formed from the melting and rapid cooling of terrestrial materials during meteorite impact events. This connection to meteorites is the key context for understanding tektites within the chapter on '14.2 Meteorites: Stones from Heaven'.
Widmanstätten Pattern: The Widmanstätten pattern is a distinctive crystalline structure observed in the cross-section of certain iron meteorites. It is characterized by a series of intersecting nickel-iron alloy bands or plates that form a unique and visually striking pattern.